At what time immediately prior to Six O'clock the hands of the clock are exactly opposite to each other.
Give the exact time in hours, minutes and seconds.
Answer
4 hrs. 54 min. 32.74 seconds
It is obvious that between 5 O'clock and 6 O'clock the hands will not be exactly opposite to each other. It is also obvious that
the hands will be opposite to each other just before 5 O'clock. Now to find exact time:
The hour hand moves 1 degree for every 12 degrees that the minute hand moves. Let the hour hand be X degree away from 5
O'clock. Therefore the minute hand is 12X degree away from 12 O'clock.
Therefore solving for X
Angle between minute hand and 12 O'clock + Angle between 12 O'clock and 4 O'clock + Angle between 4 O'clock and hour
hand = 180
12X + 120 + (30-X) = 180
11X = 30
Hence X = 30/11 degrees
(hour hand is X degree away from 5 O'clock)
Now each degree the hour hand moves is 2 minutes.
Therefore minutes are
= 2 * 30/11
= 60/11
= 5.45 (means 5 minutes 27.16 seconds)
Therefore the exact time at which the hands are opposite to each other is
= 4 hrs. 54 min. 32.74 seconds
Brain Teaser No : 00002
Ali Baba had four sons, to whom he bequeathed his 39 camels, with the proviso that the legacy be divided in the following way :
The oldest son was to receive one half the property, the next a quarter, the third an eighth and the youngest one tenth. The four
brothers were at a loss as how to divide the inheritance among themselves without cutting up a camel, until a stranger appeared
upon the scene.
Dismounting from his camel, he asked if he might help, for he knew just what to do. The brothers gratefully accepted his offer.
Adding his own camel to Ali Baba's 39, he divided the 40 as per the will. The oldest son received 20, the next 10, the third 5 and
the youngest 4. One camel remained : this was his, which he mounted and rode away.
Scratching their heads in amazement, they started calculating. The oldest thought : is not 20 greater than the half of 39? Someone
must have received less than his proper share ! But each brother discovered that he had received more than his due. How is it
possible?
Answer
They took their percentages from 40 and not from 39, so they got more than their share.
The oldest son got 1/2 of 40 = 20 which is 0.5 more
The second son got 1/4 of 40 = 10 which is 0.25 more
The third son got 1/8 of 40 = 5 which is 0.125 more
The youngest son got 1/10 of 40 = 4 which is 0.1 more
And the stranger got 1/40 of 40 = 1 which is 0.025 more (As he is not supposed to get anything)
All these fractions add to = 0.5 + 0.25 + 0.125 + 0.1 + 0.025 = 1 which stranger took away.
Brain Teaser No : 00003
In a hotel, rooms are numbered from 101 to 550. A room is chosen at random. What is the probability that room number starts with
1, 2 or 3 and ends with 4, 5 or 6?
Answer
There are total 450 rooms.
Out of which 299 room number starts with either 1, 2 or 3. (as room number 100 is not there) Now out of those 299 rooms only
90 room numbers end with 4, 5 or 6
So the probability is 90/450 i.e. 1/5 or 0.20
Brain Teaser No : 00005
A man went into a fast food restaurant and ate a meal costing Rs. 105, giving the accountant a Rs. 500 note. He kept the change,
came back a few minutes later and had some food packed for his girl friend. He gave the accountant a Rs. 100 note and received
Rs. 20 in change. Later the bank told the accountant that both the Rs. 500 and the Rs. 100 notes were counterfeit.
How much money did the restaurant lose? Ignore the profit of the food restaurant.
Answer
He lost Rs.600
First time restaurant has given food worth Rs.105 and Rs. 395 change. Similarly second time, food worth Rs.80 and Rs.20
change. Here, we are not considering food restaurant profits.
Brain Teaser No : 00006
You are working in a store that stocks bangles. Three boxes of bangles have been incorrectly labeled. The labels say Red Bangles,
Green Bangles and Red & Green Bangles.
How can you re-label the boxes correctly, by taking only one bangle from one box?
Answer
Keep in mind that boxes are incorrectly labeled.
Take out one bangle from the box labeled "Red & Green Bangles". There are 2 possibilities:
If that bangle is Red, it means that box contains Red Bangles. The box labeled as "Green Bangles" contains Red & Green
Bangles. And box labeled "Red Bangles" contains Green bangles.
RED GREEN BOX --- Red Bangles
RED BOX --- Green Bangles
GREEN BOX --- Red & Green Bangles
If that bangle is Green, it means that box contains Green
Bangles. The box labeled as "Green Bangles" contains Red
Bangles. And box labeled "Red Bangles" contains Red &
Green Bangles.
RED GREEN BOX --- Green Bangles
RED BOX --- Red & Green Bangles
GREEN BOX --- Red Bangles
Brain Teaser No : 00007
On one side of a card is written :
"THE SENTENCE ON THE OTHERSIDE OF THIS CARD IS TRUE."
On turning the card over you find:
"THE SENTENCE ON THE OTHERSIDE OF THIS CARD IS FALSE."
Which sentence is true?
Answer
It's a Paradox. Both the sentences are contradictory to each other. If you say that the first sentence is true, then the second will
contradict it and vice versa.
Brain Teaser No : 00008
3 blocks are chosen randomly on a chessboard. What is the probability that they are in the same diagonal?
Answer
There are total of 64 blocks on a chessboard. So 3 blocks can be chosen out of 64 in 64C3 ways.
So the sample space is = 41664
There are 2 diagonal on chessboard each one having 8 blocks. Consider one of them.
3 blocks out of 8 blocks in diagonal can be chosen in 8C3 ways.
But there are 2 such diagonals, hence favourables = 2 * 8C3 = 2 * 56 = 112
The require probability is
= 112 / 41664
= 1 / 372
= 0.002688
Brain Teaser No : 00010
In a contest of intelligence, three problems A, B and C were posed.
• Among the contestants there were 25 who solved at least one problem each.
• Of all the contestants who did not solve problem A, the number who solved B was twice the number who solved C.
• The number of participants who solved only problem A was one more than the number who solved problem A and at least
one other problem.
• Of all students who solved just one problem, half did not solve problem A.
How many students solved only problem B?
Answer
6 students solved only problem B
X => Students who solved only problem A
Y => Students who solved only problem B
Z => Students who solved only problem C
P => Students who solved both problem B and problem C
From 4 :
Students who solved only problem A = Students who solved only problem B + Students who solved only problem C
X = Y + Z
From 3 :
Students who solved problem A and at least one other = X - 1
From 2 :
(Y + P) = 2 * (Z + P)
Y + P = 2 * Z + 2 * P
Z = (Y - P) / 2
From 1 and Figure:
X + X - 1 + Y + Z + P = 25
2*X + Y + Z + P = 26
2*(Y + Z) + Y + Z + P = 26 (from 4)
3*Y + 3*Z + P = 26
3*Y + 3* (Y - P) / 2 + P = 26 (from 2)
6*Y + 3*Y - 3*P + 2*P = 52
9*Y - P = 52
Y = (52 + P) / 9
Now, it is obvious that all values are integer. Hence, P must be 2 and Y must be 6.
So 6 students solved only problem B.
Brain Teaser No : 00011
When Alexander the Great attacked the forces of Porus, an Indian soldier was captured by the Greeks. He had displayed such
bravery in battle, however, that the enemy offered to let him choose how he wanted to be killed. They told him, "If you tell a lie, you
will put to the sword, and if you tell the truth you will be hanged."
The soldier could make only one statement. He made that statement and went free. What did he say?
Answer
The soldier said, "You will put me to the sword."
The soldier has to say a Paradox to save himself. If his statement is true, he will be hanged, which is not the sword and hence
false. If his statement is false, he will be put to the sword, which will make it true. A Paradox !!!
Brain Teaser No : 00014
Five horses ran in the race.
• There were no ties.
• Sikandar did not come first.
• Star was neither first nor last.
• Mughal Glory came in one place after Sikandar.
• Zozo was not second.
• Rangila was two place below Zozo.
In what order did the horses finish?
Answer
It's simple.
Let's find the possible places horses can finish. Possibilities are:
Sikandar - 2,3,4 (not 5th as Mughal Glory came one place after him)
Star - 2,3,4
Mughal Glory - 3,4,5
Zozo - 1,3 (not 4th & 5th as Rangila is two place after him)
Rangila - 3,5
So the result is:
1 Zozo
2 Star
3 Rangila
4 Sikandar
5 Mughal Glory
Brain Teaser No : 00015
In the town called Alibaug, the following facts are true:
• No two inhabitants have exactly the same number of hairs.
• No inhabitants has exactly 2025 hairs.
• There are more inhabitants than there are hairs on the head of any one inhabitants.
What is the largest possible number of the inhabitants of Alibaug?
Answer
2025
It is given that no inhabitants have exactly 2025 hairs. Hence there are 2025 inhabitants with 0 to 2024 hairs in the head.
Suppose there are more than 2025 inhabitants. But these will violate the condition that "There are more inhabitants than there
are hairs on the head of any one inhabitants." As for any number more than 2025, there will be same number of inhabitants as
the maximum number of hairs on the head of any inhabitant.
Brain Teaser No : 00016
At what time after 4.00 p.m. is the minutes hand of a clock exactly aligned with the hour hand?
Answer
4:21:49.5
Assume that X minutes after 4.00 PM minute hand exactly aligns with and hour hand.
For every minute, minute hand travels 6 degrees.
Hence, for X minutes it will travel 6 * X degrees.
For every minute, hour hand travels 1/2 degrees.
Hence, for X minutes it will travel X/2 degrees.
At 4.00 PM, the angle between minute hand and hour hand is 120 degrees. Also, after X minutes, minute hand and hour hand
are exactly aligned. So the angle with respect to 12 i.e. Vertical Plane will be same. Therefore,
6 * X = 120 + X/2
12 * X = 240 + X
11 * X = 240
X = 21.8182
X = 21 minutes 49.5 seconds
Hence, at 4:21:49.5 minute hand is exactly aligned with the hour hand.
Brain Teaser No : 00017
A card contains following three sentences:
a. THIS SENTENCE CONTAINS FIVE WORDS.
b. THIS SENTENCE CONTAINS TWO VERBS.
c. EXACTLY ONE SENTENCE ON THIS CARD IS TRUE.
Is sentence C true or false?
Answer
It's a paradox.
You can’t say it true or false, as your answer will contradict itself.
Brain Teaser No : 00018
A barber in a certain small town shaves all the men who do not shave themselves, but never shaves any who do shave
themselves.
Does the barber shave himself? Note that the barber is a man.
Answer
It's a paradox.
You can't say it true or false, as your answer will contradict itself.
Brain Teaser No : 00021
A rich man died. In his will, he has divided his gold coins among his 5 sons, 5 daughters and a manager.
According to his will: First give one coin to manager. 1/5th of the remaining to the elder son. Now give one coin to the manager and
1/5th of the remaining to second son and so on..... After giving coins to 5th son, divided the remaining coins among five daughters
equally.
All should get full coins. Find the minimum number of coins he has?
Answer
We tried to find out some simple mathematical method and finally we wrote small C program to find out the answer. The
answer is 3121 coins.
Here is the breakup:
First son = 624 coins
Second son = 499 coins
Third son = 399 coins
Forth son = 319 coins
Fifth son = 255 coins
Daughters = 204 each
Manager = 5 coins
Brain Teaser No : 00022
There were N stations on a railroad. After adding X stations 46 additional tickets have to be printed.
Find N and X.
Answer
Let before adding X stations, total number of tickets
t = N(N-1)
After adding X stations total number of tickets are
t + 46 = (N+X)(N+X-1)
Subtracting 1st from 2nd
46 = (N+X)(N+X-1) - N(N-1)
46 = N2 + NX - N + NX + X2 - X - N2 + N
46 = 2NX + X2 - X
46 = (2N - 1)X + X2
X2 + (2N - 1)X - 46 = 0
Now there are only two possible factors of 46. They are (46,1) and (23,2)
Case I: (46,1)
2N - 1 = 45
2N = 46
N = 23
And X = 1
Case II: (23,2)
2N - 1 = 21
2N = 22
N = 11
And X = 2
Hence, there are 2 possible answers.
Brain Teaser No : 00023
There is a grid of 20 squares by 10 squares. How many different rectangles are possible?
Note that square is a rectangle.
Answer
11550
The Generic solution to this is:
Total number of rectangles = (Summation of row numbers) * (Summation of column numbers)
Here there are 20 rows and 10 columns or vice versa. Hence, total possible rectangles
= ( 20 + 19 + 18 + 17 + 16 + .... + 3 + 2 + 1 ) * ( 10 + 9 +8 + 7 + .... + 3 + 2 + 1)
= ( 210 ) * (55)
= 11550
Hence, total 11,550 different rectangles are possible.
If you don't believe it, try formula on some smaller grids like 4x2, 3x2, 3x3 etc...
Brain Teaser No : 00024
A person wanted to withdraw X rupees and Y paise from the bank. But cashier made a mistake and gave him Y rupees and X
paise. Neither the person nor the cashier noticed that.
After spending 20 paise, the person counts the money. And to his surprise, he has double the amount he wanted to withdraw.
Find X and Y. (1 Rupee = 100 Paise)
Answer
As given, the person wanted to withdraw 100X + Y paise.
But he got 100Y + X paise.
After spending 20 paise, he has double the amount he wanted to withdraw. Hence, the equation is
2 * (100X + Y) = 100Y + X - 20
200X + 2Y = 100Y +X - 20
199X - 98Y = -20
98Y - 199X = 20
Now, we got one equation; but there are 2 variables. We have to apply little bit of logic over here. We know that if we
interchange X & Y, amount gets double. So Y should be twice of X or one more than twice of X i.e. Y = 2X or Y = 2X+1
Case I : Y=2X
Solving two equations simultaneously
98Y - 199X = 20
Y - 2X = 0
We get X = - 20/3 & Y = - 40/2
Case II : Y=2X+1
Solving two equations simultaneously
98Y - 199X = 20
Y - 2X = 1
We get X = 26 & Y = 53
Now, its obvious that he wanted to withdraw Rs. 26.53
Brain Teaser No : 00025
What is the remainder left after dividing 1! + 2! + 3! + … + 100! By 7?
Think carefully !!!
Answer
A tricky one.
7! onwards all terms are divisible by 7 as 7 is one of the factor. So there is no remainder left for those terms i.e. remainder left
after dividing 7! + 8! + 9! + ... + 100! is 0.
The only part to be consider is
= 1! + 2! + 3! + 4! + 5! + 6!
= 1 + 2 + 6 + 24 + 120 + 720
= 873
The remainder left after dividing 873 by 7 is 5
Hence, the remainder is 5.
Brain Teaser No : 00026
Find the last digit of summation of the series:
199 + 299 + 399 + 499 + ……… + 9899 + 9999
Answer
The last digit of the series is 0.
We group the sum as follow:
(199 + 1199 + ... + 9199) + (299 + 2299 + ... 9299) + ...... + (999 + 1999 + ... + 9999) + (1099 + 2099 + 3099 + ... 9099)
All the terms in a single group have the same last digit (i.e. last digits of 199 + 1199 + ... + 9199 are same, is 1, & similarly for the
other groups).
Also, there are 10 terms in each group except for the last one. Therefore the last digit of the sum of terms in first 9 groups is 0.
(as whatever be the last digit, we have to multiply it by 10) And the last digit of the sum of the terms in the group 10 is obviously
0.
Hence, the last digit of the series is 0.
Brain Teaser No : 00027
Find the smallest number such that if its rightmost digit is placed at its left end, the new number so formed is precisely 50% larger
than the original number.
Answer
The answer is 285714.
If its rightmost digit is placed at its left end, then new number is 428571 which is 50% larger than the original number 285714.
The simplest way is to write a small program. And the other way is trial and error !!!
Brain Teaser No : 00028
There are 10 boxes containing 10 balls each. 9 boxes contain 10 balls of 10 kg each and one box contains 10 balls of 9 kg each.
Tool is available for proper weighing. How can you find out the box containing 9 kg balls?
You are allowed to weigh only once. You can remove balls from the boxes. All balls are of same size and color.
Answer
1. Mark the boxes with numbers 1, 2, 3, 4, ... upto 10
2. Take 1 ball from box 1, take 2 balls from box 2, take 3 balls from box 3, take 4 balls from box 4 and so on
3. Put all of them on the scale at once and take the measurement.
4. Now, subtract the measurement from 550 ( 1*10 + 2*10 + 3*10 + 4*10 + 5*10 + 6*10 + 7*10 + 8*10 + 9*10 + 10*10)
5. The result will give you the box number which has a ball of 9 Kg
Brain Teaser No : 00029
A fly is flying between two trains, each travelling towards each other on the same track at 60 km/h. The fly reaches one engine,
reverses itself immediately, and flies back to the other engine, repeating the process each time.
The fly is flying at 90 km/h. If the fly flies 180 km before the trains meet, how far apart were the trains initially?
Answer
Initially, the trains were 240 km apart.
The fly is flying at the speed of 90 km/h and covers 180 km. Hence, the fly flies for 2 hours after trains started.
It's obvious that trains met 2 hours after they started travelling towards each other. Also, trains were travelling at the speed of
60 km/h. So, each train traveled 120 km before they met.
Hence, the trains were 240 km apart initially.
Brain Teaser No : 00030
A certain street has 1000 buildings. A sign-maker is contracted to number the houses from 1 to 1000. How many zeroes will he
need?
Answer
The sign-maker will need 192 zeroes.
Divide 1000 building numbers into groups of 100 each as follow:
(1..100), (101..200), (201..300), ....... (901..1000)
For the first group, sign-maker will need 11 zeroes.
For group numbers 2 to 9, he will require 20 zeroes each.
And for group number 10, he will require 21 zeroes.
The total numbers of zeroes required are
= 11 + 8*20 + 21
= 11 + 160 + 21
= 192
Brain Teaser No : 00031
Find sum of digits of D.
Let
A= 19991999
B = sum of digits of A
C = sum of digits of B
D = sum of digits of C
(HINT : A = B = C = D (mod 9))
Answer
The sum of the digits od D is 1.
Let E = sum of digits of D.
It follows from the hint that A = E (mod 9)
Consider,
A = 19991999
< 20002000
= 22000 * 10002000
= 1024200 * 106000
< 10800 * 106000
= 106800
i.e. A < 106800
i.e. B < 6800 * 9 = 61200
i.e. C < 5 * 9 = 45
i.e. D < 2 * 9 = 18
i.e. E <= 9
i.e. E is a single digit number.
Also,
1999 = 1 (mod 9)
so 19991999 = 1 (mod 9)
Therefore we conclude that E=1.
Brain Teaser No : 00032
Find the smallest number N which has the following properties:
1. its decimal representation has 6 as the last digit.
2. If the last digit 6 is erased and placed in front of the remaining digits, the resulting number is four times as great as the
original number N.
Answer
The smallest such number is 153846.
Assume that the number N is
N = BnBn-1Bn-2 ... B3B26
as its given that 6 is the last digit.
Now after erasing 6 and putting it in front of the remaining digits, we get
Nnew = 6BnBn-1Bn-2 ... B3B2
Also given that Nnew is 4 times the N. Also note that the last digit Nnew is second last digit of N and so on. The required result is
BnBn-1Bn-2 ... B3B26
X 4
--------------------
6BnBn-1Bn-2 ... B3B2
So start multiplying and put nth digit of Nnew to (n + 1)th digit of N and you will get result as
1 5 3 8 4 6
X 4
---------------
6 1 5 3 8 4
Hence, the number is 153846
Brain Teaser No : 00033
There are 9 coins. Out of which one is odd one i.e weight is less or more. How many iterations of weighing are required to find odd
coin?
Answer
It is always possible to find odd coin in 3 weighings and to tell whether the odd coin is heavier or lighter.
1. Take 8 coins and weigh 4 against 4.
o If both are not equal, goto step 2
o If both are equal, goto step 3
2. One of these 8 coins is the odd one. Name the coins on heavier side of the scale as H1, H2, H3 and H4. Similarly,
name the coins on the lighter side of the scale as L1, L2, L3 and L4. Either one of H's is heavier or one of L's is lighter.
Weigh (H1, H2, L1) against (H3, H4, X) where X is one coin remaining in intial weighing.
o If both are equal, one of L2, L3, L4 is lighter. Weigh L2 against L3.
If both are equal, L4 is the odd coin and is lighter.
If L2 is light, L2 is the odd coin and is lighter.
If L3 is light, L3 is the odd coin and is lighter.
o If (H1, H2, L1) is heavier side on the scale, either H1 or H2 is heavier. Weight H1 against H2
If both are equal, there is some error.
If H1 is heavy, H1 is the odd coin and is heavier.
If H2 is heavy, H2 is the odd coin and is heavier.
o If (H3, H4, X) is heavier side on the scale, either H3 or H4 is heavier or L1 is lighter. Weight H3 against H4
If both are equal, L1 is the odd coin and is lighter.
If H3 is heavy, H3 is the odd coin and is heavier.
If H4 is heavy, H4 is the odd coin and is heavier.
3. The remaining coin X is the odd one. Weigh X against the anyone coin used in initial weighing.
o If both are equal, there is some error.
o If X is heavy, X is the odd coin and is heavier.
o If X is light, X is the odd coin and is lighter.
Brain Teaser No : 00034
My friend collects antique stamps. She purchased two, but found that she needed to raise money urgently. So she sold them for
Rs. 8000 each. On one she made 20% and on the other she lost 20%.
How much did she gain or lose in the entire transaction?
Answer
She lost Rs 666.67
Consider the first stamp. She mades 20% on it after selling it for Rs 8000.
So the original price of first stamp is
= (8000 * 100) / 80
= Rs 6666.67
Similarly, consider second stamp. She lost 20% on it after selling it for Rs 8000
So the original price of second stamp is
= (8000 * 100) / 80
= Rs 10000
Total buying price of two stamps
= Rs 6666.67 + Rs 10000
= Rs 16666.67
Total selling price of two stamps
= Rs 8000 + Rs 8000
= Rs 16000
Hence, she lost Rs 666.67
Brain Teaser No : 00035
In a sports contest there were m medals awarded on n successive days (n > 1).
1. On the first day 1 medal and 1/7 of the remaining m - 1 medals were awarded.
2. On the second day 2 medals and 1/7 of the now remaining medals was awarded; and so on.
3. On the nth and last day, the remaining n medals were awarded.
How many days did the contest last, and how many medals were awarded altogether?
Answer
Total 36 medals were awarded and the contest was for 6 days.
On day 1: Medals awarded = (1 + 35/7) = 6 : Remaining 30 medals
On day 2: Medals awarded = (2 + 28/7) = 6 : Remaining 24 medals
On day 3: Medals awarded = (3 + 21/7) = 6 : Remaining 18 medals
On day 4: Medals awarded = (4 + 14/7) = 6 : Remaining 12 medals
On day 5: Medals awarded = (5 +7/7) = 6 : Remaining 6 medals
On day 6: Medals awarded 6
I got this answer by writing small program. If anyone know any other simpler method, do submit it.
Brain Teaser No : 00036
A number of 9 digits has the following properties:
• The number comprising the leftmost two digits is divisible by 2, that comprising the leftmost three digits is divisible by 3,
the leftmost four by 4, the leftmost five by 5, and so on for the nine digits of the number i.e. the number formed from the
first n digits is divisible by n, 2<=n<=9.
• Each digit in the number is different i.e. no digits are repeated.
• The digit 0 does not occur in the number i.e. it is comprised only of the digits 1-9 in some order.
Find the number.
Answer
The answer is 381654729
One way to solve it is Trial-&-Error. You can make it bit easier as odd positions will always occupy ODD numbers and even
positions will always occupy EVEN numbers. Further 5th position will contain 5 as 0 does not occur.
The other way to solve this problem is by writing a computer program that systematically tries all possibilities.
Brain Teaser No : 00038
The population of an island consists of two and only two types of people : the knights, who invariably tell the truth and the knaves
who always lie.
• three of the inhabitants called X, Y and Z were standing together. A newcomer to the island asked, "Are you a knight or a
knave?" X mumbled his answer rather indistinctly, so the stranger could not quite make out what he had said. The
stranger than asked Y, "What did X say?" Y replied, "X said that he was a knave." Whereupon Z said, "Don't believe Y,
he's lying." What are Y and Z?
• Suppose that the stranger asked X, instead, "How many knights among you?" Again X replies indistinctly. So the stranger
asks Y, "What did X say?" Y replies, "X said that there is one knight among us." Then Z says, "Don't believe Y, he is lying!"
Now what are Y and Z?
• There are only two inhabitants, X and Y. X says, "At least one of us is a knave." What are X and Y?
• Suppose X says, "Either I am a knave, or Y is a knight?" What are X and Y?
• Consider once more X, Y and Z each of who is either a knight or a knave. X says, "All of us are knaves." Y says, "Exactly
one of us is a knight." What are X, Y and Z?
Answer
Teaser 1 : A Simple one. The statement made by Y is false - "X said that he was a knave".
Case 1 Case 2 Case 3 Case 4
X Knight Knight Knave Knave
Y Knight Knave Knight Knave
Analyse the above 4 cases. In all the cases statement made by Y is contradicory and therefore false. Hence, Y is Knave and Z
is Knight.
Teaser 2 : Again the statement made by Y is false - "X said that there is one knight among us". Analyse these statement with 4
possible cases as above. In all the cases statement made by Y is false. Hence, Y is Knave and Z is Knight.
Teaser 3 : X is Knight and Y is Knave.
Teaser 4 : Both are Knight.
Teaser 5 : X and Z are Knaves, Y is Knight.
Brain Teaser No : 00039
Find next number in the series :
3, 7, 31, 211, ?
Answer
1831
All the numbers in the series are Prime Numbers. So the next number will also be a prime number.
Two consecutive numbers in the
series
(A and B)
Total Prime numbers bewtween A
and B
(C)
Prime number just before
B
(D)
E = (C +
D)
3 and 7 1 5 6
7 and 31 6 29 35
31 and 211 35 199 234
• Number after 7 is the prime number on skipping 6 prime numbers after 7 i.e. 31
• Number after 31 is the prime number on skipping 35 prime numbers after 31 i.e. 211
• Hence, number after 211 is the prime number on skipping 234 prime numbers after 211 i.e. 1831
The other possible answer is 1891.
Subtract 1 from each number in the given series: 2, 6, 30, 210
First number = 2*1 = 2
Second number = 2*3 = 6
Third number = 6*5 = 30
Fourth number = 30*7 = 210
Fifth number = 210*9 = 1890
Sixth number = 1890*11 = 20790
Thus, the pattern is : multiply previous number by next odd number and add one to the multiplication. Thus, the series is 3, 7,
31, 211, 1891, 20791, ...
Thanks to N. Anand for this much more simpler answer.
Brain Teaser No : 00040
Assume for a moment that the earth is a perfectly uniform sphere of radius 6400 km. Suppose a thread equal to the length of the
circumference of the earth was placed along the equator, and drawn to a tight fit.
Now suppose that the length of the thread is increased by 12 cm, and that it is pulled away uniformly in all directions.
By how many cm. will the thread be separated from the earth's surface?
Answer
The cicumference of the earth is
= 2 * PI * r
= 2 * PI * 6400 km
= 2 * PI * 6400 * 1000 m
= 2 * PI * 6400 * 1000 * 100 cm
= 1280000000 * PI cm
where r = radius of the earth, PI = 3.141592654
Hence, the length of the thread is = 1280000000 * PI cm
Now length of the thread is increasd by 12 cm. So the new length is = (1280000000 * PI) + 12 cm
This thread will make one concentric circle with the earth which is slightly away from the earth. The circumfernce of that circle is
nothing but (1280000000 * PI) + 12 cm
Assume that radius of the outer circle is R cm
Therefore,
2 * PI * R = (1280000000 * PI) + 12 cm
Solving above equation, R = 640000001.908 cm
Radius of the earth is r = 640000000 cm
Hence, the thread will be separatedfrom the earth by
= R - r cm
= 640000001.908 - 640000000
= 1.908 cm
Brain Teaser No : 00041
A polygon has 1325 diagonals. How many vertices does it have?
Answer
The formula to find number of diagonals (D) given total number of vertices or sides (N) is
N * (N - 3)
D = -----------
2
Using the formula, we get
1325 * 2 = N * (N - 3)
N2 - 3N - 2650 = 0
Solving the quadratic equation, we get N = 53 or -50
It is obvious that answer is 53 as number of vertices can not be negative.
Alternatively, you can derive the formula as triange has 0 diagonals, quadrangel has 2, pentagon has 5, hexagon has 9 and so
on......
Hence the series is 0, 0, 0, 2, 5, 9, 14, ........ (as diagram with 1,2 or 3 vertices will have 0 diagonals).
Using the series one can arrive to the formula given above.
Brain Teaser No : 00042
An emergency vehicle travels 10 miles at a speed of 50 miles per hour.
How fast must the vehicle travel on the return trip if the round-trip travel time is to be 20 minutes?
Answer
75 miles per hour
While going to the destination, the vehicle travels 10 mils at the speed of 50 miles per hour. So the time taken to travel 10 miles
is
= (60 * 10) / 50
= 12 minutes
Now it's given that round-trip travel time is 20 minutes. So the vehicle should complete its return trip of 10 miles in 8 minutes.
So the speed of the vehicle must
= (60 * 10) / 8
= 75 miles per hour
Brain Teaser No : 00043
Professors Ahmad and Joshi are extremely strange persons.
Prof. Ahmad lies on Mondays, Tuesdays and Wednesdays, but tells true on other days of the week.
Prof. Joshi lies on Thursdays, Fridays and Saturdays, but tells true on other days of the week.
• They made the following statements:
Prof. Ahmad : "Yesterday was one of my lying days."
Prof. Joshi : "Yesterday was one of my lying days too."
What day of the week was it?
• Both Professors looked very alike and one day they said to a visitor to their department :
First Prof: "I'm Ahmed."
Second Prof: "I'm Joshi."
Who was who? What day of the week was it?
• On another occasion, both Professors made the following statements:
First Prof : 1. "I lie on Saturdays."
2. "I lie on Sundays."
Second Prof. : "I will lie tomorrow."
What day of the week was it?
Answer
Mon Tue Wed Thu Fri Sat Sun
Prof. Ahmad Lies Lies Lies tells truth tells truth tells truth tells truth
Prof. Joshi tells truth tells truth tells truth Lies Lies Lies tells truth
Teaser 1 :
Assume that Prof. Ahmad is telling truth => today is Thursday
Assume that Prof. Ahmad is lying => today is Monday
Similarly, Assume Prof. Joshi is telling truth => today is Sunday
Assume that Prof. Joshi is lying => today is Thrusday.
Hence, today is Thrusday, Prof. Ahmad is telling truth and Prof. Joshi is lying.
Teaser 2 :
Assume that First Prof. is telling truth => Thursday, Friday, Saturday or Sunday
Assume that First Prof. is lying => Thursday, Friday or Saturday
Similarly, Assume Second Prof. is telling truth => Monday, Tuesday, Wednesday or Sunday
Assume that Second Prof. is lying => Monday, Tuesday, Wednesday
The only possibility is Sunday and both are telling truth.
Teaser 3 :
A simple one. First Prof. says - "I lie on Sunday" which is false as both the Prof. tell truth on sunday. It means the first statement
made by the First Prof. is also false. It means the First Prof. tells truth on Saturday. Hence First Prof. is Prof. Ahmad and he is
lying. It means that today is either Monday, Tuesday or Wednesday.
It is clear that Second Prof. is Prof. Joshi.
Assume that he is telling truth => today is Wednesday
Assume that he is lying => today is Saturday.
Hence, today is Wednesday !!!
Brain Teaser No : 00045
A class of 100 students. 24 of them are girls and 32 are not. Which base am I using?
Answer
Let the base be X.
Therefore
(X*X + X*0 + 0) = (2*X +4) + (3*X + 2)
X*X = 5*X + 6
X*X - 5*X -6 = 0
(X-6)(X+1) = 0
Therefore base is 6
Brain Teaser No : 00046
What is the area of the triangle ABC with A(e,p) B(2e,3p) and C(3e,5p)?
where p = PI (3.141592654)
Answer
A tricky ONE.
Given 3 points are colinear. Hence, it is a straight line.
Hence area of triangle is 0.
Brain Teaser No : 00047
The ratio of Boys to Girls is 6:4. 60% of the boys and 40% of the girls take lunch in the canteen. What % of class takes lunch in
canteen?
Answer
Assume there are 6X boys and 4X Girls
Total Students taking lunch in canteen
= (6X)(60/100) + (4X)(40/100)
= 36(X/10) + 16(X/10)
= 52(X/10)
Total students are = 6X + 4X = 10X
% of class taking lunch in canteen
= ((52X/10) * 100 ) / 10X
= 52 %
Brain Teaser No : 00048
1/3 rd of the contents of a container evaporated on the 1st day. 3/4th of the remaining contents of the container evaporated on the
second day.
What part of the contents of the container is left at the end of the second day?
Answer
1/6th of the contents of the container is remaining.
Assume that contents of the container is X
On the first day 1/3rd is evaporated.
(1 - 1/3) of X is remaining i.e. (2/3)X
On the Second day 3/4th is evaporated. Hence,
(1- 3/4) of (2/3)X is remaining
i.e. (1/4)(2/3)X = (1/6) X
Hence 1/6th of the contents of the container is remaining.
Brain Teaser No : 00049
The average scores of the class for exam are as follow:
Average score of the boys = 90
Average score of the girls = 81
Average score of the class = 84
Find whether Class contains more Boys or Girls?
Answer
Assume that there are B boys and G girls in the Class.
Hence from the given data :
90*B + 81*G = 84*(B+G)
90B + 81G = 84B + 84G
6B = 3G
2B = G
Hence number of Girls in the Class are twice the number of Boys.
Brain Teaser No : 00050
Two identical pack of cards A and B are shuffled throughly. One card is picked from A and shuffled with B. The top card from pack
A is turned up. If this is the Queen of Hearts, what are the chances that the top card in B will be the King of Hearts?
Answer
52 / 2703
There are two cases to be considered.
CASE 1 : King of Hearts is drawn from Pack A and shuffled with Pack B
Probability of drawing King of Hearts from Pack A = 1/51 (as Queen of Hearts is not to be drawn)
Probability of having King of Hearts on the top of the Pack B = 2/53
So total probability of case 1 = (1/51) * (2/53) = 2 / (51 * 53)
CASE 2 : King of Hearts is not drawn from Pack A
Probability of not drawing King of Hearts from Pack A = 50/51 (as Queen of Hearts is not to be drawn)
Probability of having King of Hearts on the top of the Pack B = 1/53
So total probability of case 2 = (50/51) * (1/53) = 50 / (51 * 53)
Now adding both the probability, the required probability is
= 2 / (51 * 53) + 50 / (51 * 53)
= 52 / (51 * 53)
= 52 / 2703
= 0.0192378
Brain Teaser No : 00051
8 Queens Problem
In how many ways can you arrange 8 queens on a standard chessboard in such a way that none of them is attacking any other?
Answer
There are 92 ways of placing the 8 queens on the board. Some of such positions are :
1. A1, B5, C8, D6, E3, F7, G2, H4
2. A1, B6, C8, D3, E7, F4, G2, H5
3. A1, B7, C4, D6, E8, F2, G5, H3
4. A1, B7, C5, D8, E2, F4, G6, H3
The easiest way to solve this problem is by writing a computer program that systematically tries all possibilities of placing the 8
queens on the board.
Brain Teaser No : 00053
A man is going to an Antique Car auction. All purchases must be paid for in cash. He goes to the bank and draws out $25,000.
Since the man does not want to be seen carrying that much money, he places it in 15 evelopes numbered 1 through 15. Each
envelope contains the least number of bills possible of any available US currency (i.e. no two tens in place of a twenty).
At the auction he makes a successful bid of $8322 for a car. He hands the auctioneer envelopes number(s) 2, 8, and 14. After
opening the envelopes the auctioneer finds exactly the right amount.
How many ones did the auctioneer find in the envelopes?
Answer
Each envelope contains the money equal to the 2 raised to the envelope number minus 1. The sentence "Each envelope
contains the least number of bills possible of any available US currency" is only to misguide you. This is always possible for any
amount !!!
One more thing to notice here is that the man must have placed money in envelopes in such a way that if he bids for any
amount less than $25000, he should be able to pick them in terms of envelopes.
First envelope contains, 20 = $1
Second envelope contains, 21 = $2
Third envelope contains, 22 = $4
Fourth envelope contains, 23 = $8 and so on...
Hence the amount in envelopes are $1, $2, $4, $8, $16, $32, $64, $128, $256, $512, $1024, $2048, $4096, $8192, $8617
Last envelope (No. 15) contains only $8617 as total amount is only $25000.
Now as he bids for $8322 and gives envelope number 2, 8 and 14 which contains $2, $128 and $8192 respectively.
Envelope No 2 conrains one $2 bill
Envelope No 8 conrains one $100 bill, one $20 bill, one $5 bill, one $2 bill and one $1 bill
Envelope No 14 conrains eighty-one $100 bill, one $50 bill, four $10 bill and one $2 bill
Hence the auctioneer will find one $1 bill in the envelopes.
Brain Teaser No : 00054
There is a man who lives on the top floor of a very tall building. Everyday he gets the elevator down to the ground floor to leave the
building to go to work.
Upon returning from work though, he can only travel half way up in the lift and has to walk the rest of the way unless it's raining!
Why?
Answer
This is probably the best known and most celebrated of all lateral thinking puzzles. It is a true classic.
The man is very, very short and can only reach halfway up the elevator buttons. However, if it is raining then he will have his
umbrella with him and can press the higher buttons with it.
Brain Teaser No : 00055
A man and his son are in a car accident. The father dies on the scene, but the child is rushed to the hospital. When he arrives the
surgeon says, "I can't operate on this boy, he is my son!"
How can this be?
Answer
This is a lateral thinking puzzle.
The surgeon was his mother.
Also, the doctor could be the boy's biological father, and the man in the car could be the step or legal father.
Brain Teaser No : 00056
A man is wearing black. Black shoes, socks, trousers, jumper, gloves and balaclava. He is walking down a black street with all the
street lamps off. A black car is coming towards him with its light off but somehow manages to stop in time.
How did the driver see the man?
Answer
This is a lateral thinking puzzle.
It was day time.
Brain Teaser No : 00057
One day Kerry celebrated her birthday. Two days later her older twin brother, Terry, celebrated his birthday.
How? Note that they both celebrated their birthday on their actual birthdays.
Answer
This is a lateral thinking puzzle.
At the time she went into labor, the mother of the twins was traveling by boat. The older twin, Terry, was born first early on
March 1st. The boat then crossed a time zone and Kerry, the younger twin, was born on February the 28th. Therefore, the
younger twin celebrates her birthday two days before her older brother.
There is one more answer submitted by Beano.
She obviously had an older set of twin brothers and their birthday was 2 days after hers, they just didn't mention that it was also
her other twin brothers birthday.
Also, according to Robbie TWINS DONT HAVE TO HAVE THE SAME BIRTHDAY! SOME TWINS ARE BORN 300 DAYS
APART !!!
Brain Teaser No : 00058
Why is it better to have round manhole covers than square ones?
Answer
This is a lateral thinking puzzle. Also, the MOST asked question during interview.
A square manhole cover can be turned and dropped down the diagonal of the manhole. A round manhole cover cannot be
dropped down the manhole. So for safety and practicality, all manhole covers should be round.
Brain Teaser No : 00059
A man went to a party and drank some of the punch. He then left early. Everyone else at the party who drank the punch
subsequently died of poisoning.
Why did the man not die? Please note that he did not add the poison. Also, nothing was added to punch after he left.
Answer
This is a lateral thinking puzzle.
The poison in the punch came from the ice cubes. When the man drank the punch, the ice was fully frozen. Gradually it melted,
poisoning the punch.
Brain Teaser No : 00060
A woman had two sons who were born on the same hour of the same day of the same month of the same year. But they were not
twins.
How could this be so?
Answer
This is a lateral thinking puzzle.
They were two of a set of triplets (or quadruplets, etc.).
This puzzle stumps many people. They try outlandish solutions involving test-tube babies or surrogate mothers. Why does the
brain search for complex solutions when there is a much simpler one available?
Brain Teaser No : 00061
Three friends check into a hotel for the night and the clerk tells them the bill is Rs. 30, payable in advance. So, they each pay the
clerk RS. 10 and go to their room.
A few minutes later, the clerk realizes he has made an error and overcharged the trio by Rs 5. He asks the hotel-boy to return Rs. 5
to the 3 friends who had just checked in. The hotel-boy sees this as an opportunity to make Rs. 2 as he reasons that the three
friends would have a tough time dividing Rs. 5 evenly among them; so he decides to tell them that the clerk made a mistake of only
Rs. 3, giving a rupee back to each of the friends. He pockets the leftover Rs. 2 and goes home for the day!
Now, each of the three friends gets a rupee back, thus they each paid Rs. 9 for the room which is a total of Rs. 27 for the night. We
know the hotel-boy pocketed Rs. 2 and adding that to the Rs. 27, you get Rs. 29, not Rs. 30 which was originally spent.
Where did the other rupee go???
Answer
The facts in this riddle are clear: There is an initial Rs. 30 charge. It should have been Rs. 25, so Rs.5 must be returned and
accounted for. Rs. 3 is given to the 3 friends, Rs. 2 is kept by the hotel-boy - there you have the Rs. 5.
The trick to this riddle is that the addition and subtraction are done at the wrong times to misdirect your thinking - and quite
successfully for most. Each of the 3 friends did indeed pay Rs. 9, not Rs. 10, and as far as the friends are concerned, they paid
Rs. 27 for the night. But we know that the clerk will tell us that they were charged only Rs. 25 and when you add the Rs. 3
returned with the Rs. 2 kept by the hotel-boy, you come up with Rs. 30
Brain Teaser No : 00062
It happens once in a minute, twice in a week, and once in a year? What is it?
Answer
Letter 'e'
Brain Teaser No : 00063
Sita has six pairs of black gloves and six pairs of brown gloves in her drawer.
In complete darkness, how many gloves must she take from the drawer in order to be sure to get a matching pair (i.e. left hand and
right hand golves of the same color)? Think carefully!!
Answer
13
She could possibly take out 6 black left hand gloves and then 6 brown left hand gloves, the next one would have to be either
the right hand or left hand match.
Brain Teaser No : 00064
What is the largest possible number you can write using only 2 digits? (any two digits once or same digit twice)
Answer
99
that is 9 * 9 * 9 *9 * 9 * 9 * 9 * 9 * 9 or 387,420,489
Brain Teaser No : 00065
Because cigars cannot be entirely smoked, a Bobo who collects cigar butts can make a cigar to smoke out of every 3 butts that he
finds.
Today, he has collected 27 cigar butts. How many cigars will he be able to smoke?
Answer
13 not 12
He makes 9 originals from the 27 butts he found, and after he smokes them he has 9 butts left for another 3 cigars. And then
he has 3 butts for another cigar.
So 9+3+1=13
Brain Teaser No : 00066
Someone at a party introduces you to your mother's only sister's husband's only sister-in-law. She has no brothers.
What do you call this lady?
Answer
Mother or Mom
Brain Teaser No : 00067
Two planes take off at the same exact moment. They are flying across the Atlantic. One leaves New York and is flying to Paris at
500 miles per hour. The other leaves Paris and is flying to New York at only 450 miles per hour ( because of a strong head wind ).
Which one will be closer to Paris when they meet?
Answer
They will both be the same distance from Paris when they meet!!!
Brain Teaser No : 00068
In your sock drawer, you have a ratio of 5 pairs of blue socks, 4 pairs of brown socks, and 6 pairs of black socks.
In complete darkness, how many socks would you need to pull out to get a matching pair of the same color?
Answer
4 If you don't agree, try it yourself!
Brain Teaser No : 00071
In training for a competition, you find that swimming downstream (with the current) in a river, you can swim 2 miles in 40 minutes, &
upstream (against the current), you can swim 2 miles in 60 minutes.
How long would it take you to swim a mile in still water?
Answer
You are able to swim downstream at 3 miles an hour, & upstream at 2 miles an hour. There is a difference of 1 mile an hour,
which is the river helping you in 1 direction, & slowing you in the other direction.
Average the 2 rates, & you have the rate that you can swim in still water, which is 2.5 miles an hour.
You can thus swim a mile in still water in 24 minutes.
Brain Teaser No : 00069
A woman goes into a hardware store to buy something for her house. When asked the price, the clerk replies, "the price of one is
twelve cents, the price of forty-four is twenty-four cents, and the price a hundred and forty-four is thirty-six cents.
What does the woman want to buy?
Answer
House numbers.
Price of one i.e. 1 = 12 cents (as only number 1)
Price of forty-four i.e. 44 = 24 cents (as there are two numbers)
Price of a hundred and forty-four i.e. 144 = 36 cents (as there are three numbers)
Brain Teaser No : 00075
If you take a marker & start from a corner on a cube, what is the maximum number of edges you can trace across if you never trace
across the same edge twice, never remove the marker from the cube, & never trace anywhere on the cube, except for the corners
& edges?
Answer
9
To verify this, you can make a drawing of a cube, & number each of its 12 edges. Then, always starting from 1 corner & 1 edge,
you can determine all of the possible combinations for tracing along the edges of a cube.
There is no need to start from other corners or edges of the cube, as you will only be repeating the same combinations. The
process is a little more involved than this, but is useful for solving many types of spatial puzzles.
Brain Teaser No : 00076
A cube is made of a white material, but the exterior is painted black.
If the cube is cut into 125 smaller cubes of exactly the same size, how many of the cubes will have atleast 2 of their sides painted
black?
Answer
44
36 of the cubes have EXACTLY 2 of their sides painted black, but because a cube with 3 of its sides painted black has 2 of its
sides painted black, you must also include the corner cubes. This was a trick question, but hopefully the title of the puzzle
tipped you off to this.
Brain Teaser No : 00077
In another galaxy, a certain nation of creatures speak a language known as Algramara. In this language, "harvec tood zevac"
means "my tooth hurts", "lavec lina zevac" means "my delicious food", & "zevac corma lina" means "eating my food".
What does "corma harvec zevac tood" mean?
Answer
There are 3 sentances:
1. "harvec tood zevac" means "my tooth hurts,"
2. "lavec lina zevac" means "my delicious food,"
3. "zevac corma lina" means "eating my food."
From (1), (2) & (3) "zevac" means my
From (2) & (3) "lina" means food
So From (3) "corma" means eating
and From (2) "lavec" means delicious
Now, two unknown words are there: "harvec" and "tood" which means tooth or hurts. So there are two options:
1. Eating hurts my tooth
2. Eating tooth my hurts
Only first option makes sence. So "corma harvec zevac tood" means "Eating hurts my tooth"
Brain Teaser No : 00078
PRIMAL SERIES
Decide what the next 5 figures in this series should be:
0110101000101000101000
Answer
10000
The title holds a hint, although this is still a tough puzzle. The series begins with the number 1, & continues through 22, giving a
1 for each prime number, & a 0 for each number that is not prime.
Of the last 5 numbers (23-27), only 23 is prime
Brain Teaser No : 00079
If you started a business in which you earned Rs.1 on the first day, Rs.3 on the second day, Rs.5 on the third day, Rs.7 on the
fourth day, & so on.
How much would you have earned with this business after 50 years (assuming there are exactly 365 days in every year)?
Answer
Rs.333,062,500
To begin with, you want to know the total number of days: 365 x 50 = 18250.
By experimentation, the following formula can be discovered, & used to determine the amount earned for any particular day: 1
+ 2(x-1), with x being the number of the day. Take half of the 18250 days, & pair them up with the other half in the following
way: day 1 with day 18250, day 2 with day 18249, & so on, & you will see that if you add these pairs together, they always
equal Rs.36500.
Multiply this number by the total number of pairs (9125), & you have the amount you would have earned in 50 years.
Math gurus may use series formula to solve it.(series: 1,3,5,7,9,11.....upto 18250 terms)
Brain Teaser No : 00080
A worker earns a 5% raise. A year later, the worker receives a 2.5% cut in pay, & now his salary is Rs. 22702.68
What was his salary to begin with?
Answer
Rs.22176
Assume his salary was Rs. X
He earns 5% raise. So his salary is (105*X)/100
A year later he receives 2.5% cut. So his salary is ((105*X)/100)*(97.5/100) which is Rs. 22702.68
Hence, solving equation ((105*X)/100)*(97.5/100) = 22702.68
X = 22176
Brain Teaser No : 00081
You have 9 marbles. 8 marbles weigh 1 ounce each, & one marble weighs 1.5 ounces. You are unable to determine which is the
heavier marble by looking at them. You have a weighing scale that consists of 2 pans, but the scale is only good for 2 total
weighings.
How can you determine which marble is the heaviest one using the scale & in 2 weighings?
Answer
Divide 9 marbles into 3 groups of 3 marbles each.
Take any 2 groups and place them on each pan. If they balance, remove the marbles from the pans, & place any 2 of the
marbles from the remaining unweighed group on the pans, 1 on each pan.
If one is heavier, it is the heavier marble, but if they balance, the remaining unweighed marble is the heavier one.
If your first weighing does not balance, remove the marbles from the lighter pan, & place 1 marble on each pan from the
heavier pan. The heavier 1 is the 1.5 ounce marble, but if they balance, then the marble from the heavy pan from the first
weighing that was not weighed in the second weighing is the heavy 1.
Brain Teaser No : 00083
A group of 4 people, Andy, Brenda, Carl, & Dana, arrive in a car near a friend's house, who is having a large party. It is raining
heavily, & the group was forced to park around the block from the house because of the lack of available parking spaces due to the
large number of people at the party.
The group has only 1 umbrella, & agrees to share it by having Andy, the fastest, walk with each person into the house, & then
return each time. It takes Andy 1 minute to walk each way, 2 minutes for Brenda, 5 minutes for Carl, & 10 minutes for Dana. It thus
appears that it will take a total of 19 minutes to get everyone into the house.
However, Dana indicates that everyone can get into the house in 17 minutes by a different method. How?
The individuals must use the umbrella to get to & from the house, & only 2 people can go at a time (& no funny stuff like riding on
someone's back, throwing the umbrella, etc.)
Answer
There are 2 possible answers, both of which are almost the same:
Answer 1: Andy & Brenda walk together to the house (2 minutes), & Andy returns (1 minute). Carl & Dana walk to the house
(10 minutes), & Brenda returns with the umbrella (2 minutes). Andy & Brenda walk to the house again (2 minutes).
Answer 2: Andy & Brenda walk together to the house (2 minutes), & Brenda returns (2 minutes). Carl & Dana walk to the
house (10 minutes), & Andy returns with the umbrella (1 minute). Andy & Brenda walk to the house again (2 minutes).
Brain Teaser No : 00084
You are in a room with 2 doors leading out. Behind 1 door is a coffer overflowing with jewels & gold, along with an exit. Behind the
other door is an enormous, hungry lion that will pounce on anyone opening the door. You do not know which door leads to the
treasure & exit, & which door leads to the lion.
In the room you are in, are 2 individuals. The first is a knight, who always tells the truth, & a knave, who always lies. Both of these
individuals know what is behind each door. You do not know which individual is the knight, or which one is the knave.
You may ask 1 of the individuals exactly 1 question. What should you ask in order to be certain that you will open the door with the
coffer behind it, instead of the hungry lion?
Answer
There are 2 possible answers for this puzzle:
Answer 1: You ask one of the individuals what the other one would say if you asked him or her which door you should open to
get to the coffer. In this case, you would open the other door.
Answer 2: You ask one of the individuals what the other one would say if you asked him or her which door is holding back the
hungry lion. In this case, you would open this door.
Brain Teaser No : 00086
A prisoner is told "If you tell a lie we will hang you; if you tell the truth we will shoot you."
What can he say to save himself? Note that he must say something to save himself.
Answer
You will hang me.
Brain Teaser No : 00087
Find the next number in the series 11 12 20 23 33 46 .....
Answer
All the numbers given are the fibonacci numbers in increasing bases starting 2 !!!
Therefore,
11 = 3 base 2
12 = 5 base 3
20 = 8 base 4
23 = 13 base5 etc ...
Answer = 67 which is 55 base 8
(Fibonacci series : 2, 3, 5, 8, 13, 21, 34, 55, 89..... where next number is sum of the previous to numbers.)
Brain Teaser No : 00089
There are 20 poles with a constant distance between each pole. A car takes 24 second to reach the 12th pole.
How much will it take to reach the last pole.
Answer
The car will take 41.45 seconds to reach the last pole.
Let the distance between two poles is X.
The car takes 24 seconds to reach the 12th pole. It means it travels distance of 11X in 24 seconds.
To reach the 20th pole car has to travel 19X. So time taken to reach there is
= (19X * 24) / 11X
= (19 * 24) / 11
= 41.45 seconds
Brain Teaser No : 00090
The minute and the hour hand of a watch meet every 65 minutes.
How much does the watch lose or gain time and by how much?
Answer
The minute and the hour hand meet 11 times in 12 hours in normal watch i.e. they meet after every
= (12 * 60) / 11 minutes
= 65.45 minutes
= 65 minutes 27.16 seconds
But in our case they meet after every 65 minutes means the watch is gaining 27.16 seconds.
Brain Teaser No : 00091
Father's age is three years more than three times the son's age. After three years, father's age will be ten years more than twice the
son's age.
What is the father's present age?
Answer
Let son's present age is X years.
Hence, father's present age is (3X + 3) years.
After 3 years, son's age will be (X + 3) years.
and father's age will be (3X + 6) years.
But given that after 3 years father's age will be ten years more than twice the son's age.
(3X + 6) = 2 * (X + 3) + 10
3X + 6 = 2X + 16
X = 10
Therefore, father's present age is 33 years.
Brain Teaser No : 00092
Below is a Quiz written by Einstein in the lst century.
He said 98% of the people in the world cannot solve the quiz. Are you among the other 2%?
FACTS
1. There are 5 houses in 5 different colors.
2. In each house lives a person with a different nationality.
3. These 5 owners drink a certain beverage, smoke a certain brand of cigar and keep a certain pet.
4. No owners have the same pet, smoke the same brand of cigar or drink the same drink.
HINTS
1. The Brit lives in a red house.
2. The Swede keeps dogs as pets.
3. The Dane drinks tea.
4. The green house is on the immediate left of the white house.
5. The green house owner drinks coffee.
6. The person who smokes Pall Mall rears birds.
7. The owner of the yellow house smokes Dunhill.
8. The man living in the house right in the center drinks milk.
9. The Norwegian lives in the first house.
10. The man who smokes blend lives next to the one who keeps cats.
11. The man who keeps horses lives next to the man who smokes Dunhill.
12. The owner who smokes Blue Master drinks beer.
13. The German smokes Prince.
14. The Norwegian lives next to the Blue House.
15. The man who smokes blend has a neighbor who drinks water.
THE QUESTION IS....WHO KEEPS FISH?
There is no trick to this - it needs deductive reasoning and definitely a pen and paper.
Answer
Nationality Beverage Cigar Pet House Color
------------------------------------------------------
Norwegian Water Dunhill Cat Yellow
Dane Tea Blend Horses Blue
Brit Milk Pall Mall Bird Red
German Coffee Prince Fish Green
Swede Beer Blue Master Dog White
Therefore the answer is the German.
I wonder if U could work it out by realizing that Einstien was a german and kept fish but that would probably be cheating :)
There is one more possible answer, if we remove "immediate" from the Hint 4 i.e. read it as "The green house is on the left of
the white house, not necessarily on the immediate left"
Nationality Beverage Cigar Pet House Color
------------------------------------------------------
Norwegian Coffee Blend Fish Green
German Water Prince Cats Blue
Swede Milk Dunhill Dogs Yellow
Brit Beer Blue Master Horses Red
Dane Tea Pall Mall Birds White
Thus, either German or Norwegian keeps the Fish, if the green house is not necessarily on the immediate left of the white
house.
Thanks to Katie Crowe and friends for the second answer !!!
Brain Teaser No : 00094
There are 3 ants at 3 corners of a triangle, they randomly start moving towards another corner.
What is the probability that they don't collide?
Answer
Let's mark the corners of the triangle as A,B,C. There are total 8 ways in which ants can move.
1. A->B, B->C, C->A
2. A->B, B->C, C->B
3. A->B, B->A, C->A
4. A->B, B->A, C->B
5. A->C, C->B, B->A
6. A->C, C->B, B->C
7. A->C, C->A, B->A
8. A->C, C->A, B->C
Out of which, there are only two cases under which the ants won't collide :
• A->B, B->C, C->A
• A->C, C->B, B->A
Therefore, probability of ants not colliding : 2/8 = 1/4
Brain Teaser No : 00096
If you are on a boat and you throw out a suitcase, will the level of water increase? Please note that the boat is in river and you
throw out a suitcase in the river.
Answer
No since the weight of the suitcase was already pushing on the water while it was on the boat.
Brain Teaser No : 00097
You have two jars, 50 red marbles and 50 blue marbles. A jar will be picked at random, and then a marble will be picked from the
jar. You can place maximum of 50 marbles in each jar.
Placing all of the marbles in the jars, how can you maximize the chances of a red marble being picked? What are the exact odds of
getting a red marble using your scheme?
Answer
It doesn't matter how you put the marbles in the jar.
Chances of picking a Red marble is the same. i.e. 50%
Brain Teaser No : 00098
Imagine that you have 26 constants, labelled A through Z. Each constant is assigned a value in the following way: A = 1; the rest of
the values equal their position in the alphabet (B corresponds to the second position so it equals 2, C = 3, etc.) raised to the power
of the preceeding constant value. So, B = 2 ^ (A's value), or B = 2^1 = 2. C = 3^2 = 9. D = 4^9, etc.
Find the exact numerical value to the following equation: (X - A) * (X - B) * (X - C) * ... * (X - Y) * (X - Z)
Answer
(X - A) * (X - B) * (X - C) * ... * (X - Y) * (X - Z) equals 0 since (X - X) is zero.
Brain Teaser No : 00099
You have someone working for you for seven days and a gold bar to pay them. The gold bar is segmented into seven connected
pieces. You must give them a piece of gold at the end of every day.
If you are only allowed to make two breaks in the gold bar, how do you pay your worker?
Answer
Make two breaks such that you get three segments with 1 piece, 2 pieces and 4 pieces and follow as below:
Day 1 : Give a single segment to the worker.
Day 2 : Ask the worker to return the segment you gave him on day 1 and give him the segment with Two connected pieces.
Day 3 : GIve the worker the 1 piece segment you have.
Day 4 : Ask the worker to return all pieces he has (one segment and 2 segment pieces) and give him the segment with 4 pieces
on it.
Day 5 : Give him the the segment with 1 piece.
Day 6 : Ask him to return the 1 piece segment and give him the segment with two pieces.
Day 7 : Give him the 1 piece segment you have.
Brain Teaser No : 00101
A man throws an object a certain distance; it stops momentarily and returns. It is not a boomerang and does not touch anything.
How?
Answer
The man throws the object vertically upward, perpendicular to the ground.
When you throw an object vertically up, it stops for a moment and then returns back.
Brain Teaser No : 00103
Three friends divided some bullets equally. After all of them shot 4 bullets the total number of bullets remaining is equal to the
bullets each had after division. Find the original number divided.
Answer
18
Assume that initial there were 3*X bullets.
So they got X bullets each after division.
All of them shot 4 bullets. So now they have (X - 4) bullets each.
But it is given that,after they shot 4 bullets each, total number of bullets remaining is equal to the bullets each had after division
i.e. X
Therefore, the equation is
3 * (X - 4) = X
3 * X - 12 = X
2 * X = 12
X = 6
Therefore the total bullets before division is = 3 * X = 18
Brain Teaser No : 00104
A farmer needs 8 gallons of water. He has only three unmared buckets, two 6 gallon and one 11 gallon bucket.
How can he collect 8 gallons of water using three unmarked buckets? Provide solution with minimal water wastage.
Answer
Here is the solution with 10 gallon water wastage.
OPERATIONS 6 6 11
Fill 6 gallon bucket with water 6 0 0
Empty 6 gallon bucket into 11 gallon bucket 0 0 6
Fill 6 gallon bucket with water 6 0 6
Fill 11 gallon bucket to full using filled 6 gallon bucket. This will leave 1 gallon water in 6 gallon bucket 1 0 11
Empty 11 gallon bucket into second 6 gallon bucket. 1 6 5
Empty 11 gallon bucket - wastage of 5 gallon water 1 6 0
Empty second 6 gallon bucket into 11 gallon bucket 1 0 6
Fill seccond 6 gallon bucket with water 1 6 6
Fill 11 gallon bucket to full using filled second 6 gallon bucket. This will leave 1 gallon water in second 6 gallon
bucket 1 1 11
Fill first 6 gallon bucket with 1 gallon water which is in second 6 gallon bucket 2 0 11
Empty 11 gallon bucket into second 6 gallon bucket. 2 6 5
Empty 11 gallon bucket - wastage of 5 gallon water 2 6 0
Fill 11 gallon bucket with water in both the 6 gallon buckets 0 0 11
Brain Teaser No : 00106
A ship went on a voyage. After it had travelled 180 miles a plane statrted with 10 times the speed of the ship. Find the distance
when they meet from starting point.
Answer
200 miles
Given that speed of the plane is 10 times the speed of the ship. So it is obvious that the distance covered by plane will be 10
times the distance covered by the ship for the given time.
i.e. Distance covered by plane = 10 * (Distance covered by ship after plane started)
Now from the given data,
Distance covered by plane = 180 + Distance covered by ship after plane started
10 * (Distance covered by ship after plane started) = 180 + Distance covered by ship after plane started
9 * (Distance covered by ship after plane started) = 180
Distance covered by ship after plane started = 20 miles
Total distance covered by ship from starting point
= 180 + 20
= 200 miles
Brain Teaser No : 00107
If you look at a clock and the time is 3:15.
What is the angle between the hour and the minute hands? ( The answer to this is not zero!)
Answer
7.5 degrees
At 3:15 minute hand will be perfactly horizontal pointing towards 3. Whereas hour hand will be towards 4. Also, hour hand must
have covered 1/4 of angle between 3 and 4.
The angle between two adjacent digits is 360/12 = 30 degrees.
Hence 1/4 of it is 7.5 degrees.
Brain Teaser No : 00109
There were two men standing on a street. The one says to the other, "I have 3 daughters, the product of their ages is 36. What is
the age of the OLDEST daughter?"
The second guy says, "I need more information." So, the first guy says, "The sum of their ages is equal to the address of the house
across the street."
The second guy looks at the address and says, "I still need more information." So, the first guy says, "My oldest daughter wears a
red dress."
Answer
The answer is 9 years.
First you need to find all the possible sets of three numbers that when multiplied equals 36:
1 1 36
1 2 18
1 3 12
1 4 9
1 6 6
2 2 9
2 3 6
3 3 4
Then you add the numbers together to find the sum
1 1 36 = 38
1 2 18 = 21
1 3 12 = 16
1 4 9 = 14
1 6 6 = 13
2 2 9 = 13
2 3 6 = 11
3 3 4 = 10
Even though we don't know the address the guy knows it. For him to need more information that means that at least two of the
sets of numbers has the same sum. Two of them do, 1 6 6 and 2 2 9.
When the first guy said that his OLDEST daugher wears a red dress that meant that there had to be the oldest. So 1 6 6 can't
possibly be the answer. So the possible possiblity is 2 2 9 and the OLDEST daughter is 9 years old.
Therefore, the answer is 9.
Brain Teaser No : 00110
In a certain game, if 2 wixsomes are worth 3 changs, and 4 changs are worth 1 plut, then 6 plutes are worth how many wixsomes?
Answer
It is given that
2 wixsomes = 3 changs
8 wixsomes = 12 changs ----- (I)
Also, given that
4 changs = 1 plut
12 changs = 3 plutes
8 wixsomes = 3 plutes ----- From (I)
Therefore,
6 plutes = 16 wixsomes
Brain Teaser No : 00112
A hole that is 3 feet deep, and 6 inches in diameter, has how much dirt in it..?
Answer
A tricky one.
It's a hole. So there is no dirt in it.
Brain Teaser No : 00113
The Bulls, Pacers, Lakers and Jazz ran for a contest.
Anup, Sujit, John made the following statements regarding results.
• Anup said either Bulls or Jazz will definitely win
• Sujit said he is confident that Bulls will not win
• John said he is confident that neither Jazz nor Lakers will win
When the result came, it was found that only one of the above three had made a correct statement. Who has made the correct
statement and who has won the contest?
Answer
Sujith has made the correct statement and Lakers has won the contest.
Let's solve it. Create the table with the statements made.
Bulls Pacers Lakers Jazz
Anup YES YES
Sujit NO
John NO NO
Now let's analyse the situation by assuming that Anup has made the correct statement. It means that either Bulls or Jazz has
won the contest.
• If bulls has won, then John is also correct
• If Jazz has won, then Sujit is also correct.
In either case Anup has made the wrong statement.
Now assume that Sujit has made the correct statement. It means that either or Pacers or Lakers or Jazz won the contest.
• If Pacers has won, then John is also correct.
• If Jazz has won, then Anup is also correct.
• If Lakers has won, then Anup and John both are wrong.
So is the answer - Sujit has made the correct statement and Lakers won the contest.
Similarly, analyse for john which means either Bulls or Pacershas won the contest.
Brain Teaser No : 00114
Everyday in his business a merchant had to weigh amounts from 1 kg to 121 kgs, to the nearest kg. What are the minimum number
of different weights required and how heavy should they be?
Answer
The minimum number is 5 and they should weigh 1, 3, 9, 27 and 81 kgs.
Brain Teaser No : 00115
Four prisoners escape from a prison.
The prisoners, Mr. East, Mr. West, Mr. South, Mr. North head towards different directions after escaping.
The following information of their escape was supplied:
• The escape routes were North Road, South Road, East Road and West Road
• None of the prisoners took the road which was their namesake
• Mr. East did not take the South Road
• Mr.West did not the South Road
• The West Road was not taken by Mr. East
What road did each of the prisoners take to make their escape?
Answer
Put all the given information into the table structure as follow:
North Road South Road East Road West Road
Mr. North No
Mr. South No
Mr. East No No No
Mr. West No No
Now from table, two things are obvious and they are:
• Mr.North took the South Road
• Mr.East took the North Road
Put this information into the table, Also keep in mind that the prisoners head towards different directions after escaping.
North Road South Road East Road West Road
Mr. North No YES No No
Mr. South No No
Mr. East YES No No No
Mr. West No No No
Now from the table:
• Mr.West took the East Road
• Mr.South took the West Road
So the answer is:
• Mr.North took the South Road
• Mr.South took the West Road
• Mr.East took the North Road
• Mr.West took the East Road
Brain Teaser No : 00117
I bought a car with a peculiar 5 digit numbered licence plate which on reversing could still be read. On reversing value is increased
by 78633.
Whats the original number if all digits are different?
Answer
Only 0 1 6 8 and 9 can be read upside down. So on rearranging these digits we get the answer as 10968.
Brain Teaser No : 00118
Shahrukh speaks truth only in the morning and lies in the afternoon, whereas Salman speaks truth only in the afternoon and lies in
the morning.
A says that B is Shahrukh.
Is it morning or afternoon and who is A - Shahrukh or Salman?
Answer
It is Afternoon and A can be Salman or Shahrukh. If A is Salman, he is speaking truth. If A is Shahrukh, he is lying.
Want to confirm it? Consider following 4 possible answers and check for its truthness individually.
1. It is Morning and A is Shahrukh
2. It is Morning and A is Salman
3. It is Afternoon and A is Shahrukh
4. It is Afternoon and A is Salman
Brain Teaser No : 00119
Next number in the series is 1, 2, 4, 13, 31, 112, ?
Answer
224
A tough one. But analyse the series carefully. No number has digits more than 4. So try to convert them to decimal numbers
from base 5 numbers. (just try that) So it turns out to be:
1, 2, 4, 8, 16 , 32 , ?
Got it !!! Next number should be 64. But all numbers in actual series are base 5 numbers So convert 64 to base 5 and that is
224.
Brain Teaser No : 00119
Next number in the series is 1, 2, 4, 13, 31, 112, ?
Answer
224
A tough one. But analyse the series carefully. No number has digits more than 4. So try to convert them to decimal numbers
from base 5 numbers. (just try that) So it turns out to be:
1, 2, 4, 8, 16 , 32 , ?
Got it !!! Next number should be 64. But all numbers in actual series are base 5 numbers So convert 64 to base 5 and that is
224.
Brain Teaser No : 00121
Jack and Jill are playing cards for a stake of $1 a game. At the end of the evening, Jack has won 3 games and Jill has won $3. How
many games did they play?
Submitted by : Nathalie Drouin
Answer
They played total of 9 games. Jack won 3 games and Jill won 6 games.
If Jack has won three games and Jill has won $3, she lost a dollar for each loss, therefore she has won 6 and lost 3 to make $3
and he won the other 3 that she lost!
Brain Teaser No : 00123
A soldier looses his way in a thick jungle. At random he walks from his camp but mathematically in an interesting fashion.
First he walks one mile East then half mile to North. Then 1/4 mile to West, then 1/8 mile to South and so on making a loop.
Finally how far he is from his camp and in which direction?
Answer
The soldier is 0.8944 miles away from his camp towards East-North.
It is obvious that he is in East-North direction.
Distance travelled in North and South directions
= 1/2 - 1/8 + 1/32 - 1/128 + 1/512 - 1/2048 + and so on... (a geometric series with r = (-1/4) )
(1/2) * ( 1 - (-1/4)n )
= ---------------------------
( 1 - (-1/4) )
= 1 / ( 2 * ( 1 - (-1/4) ) )
= 2/5
Similarly in East and West directions
= 1 - 1/4 + 1/16 - 1/64 + 1/256 - and so on... (a geometric series with r = (-1/4) )
(1) * ( 1 - (-1/4)n )
= ---------------------------
( 1 - (-1/4) )
= 1 / ( ( 1- (-1/4) )
= 4/5
So the soldier is 4/5 miles away towards East and 2/5 miles away towards North. So using right angled triangle, soldier is
0.8944 miles away from his camp.
Brain Teaser No : 00124
How can 1,000,000,000 be written as a product of two factors neither of them containing zeros?
Answer
29 * 59 or
(2 * 5)9
Solution submitted by Craig :
512 * 1,953,125 = 1,000,000,000
Brain Teaser No : 00125
A person with some money spends 1/3 for cloths, 1/5 of the remaining for food and 1/4 of the remaining for travel. He is left with Rs
100/-
How much did he have with him in the begining?
Answer
Rs. 250/-
Assume that initially he had Rs. X
He spent 1/3 for cloths =. (1/3) * X
Remaining money = (2/3) * X
He spent 1/5 of remaining money for food = (1/5) * (2/3) * X = (2/15) * X
Remaining money = (2/3) * X - (2/15) * X = (8/15) * X
Again, he spent 1/4 of remaining maoney for travel = (1/4) * (8/15) * X = (2/15) * X
Remaining money = (8/15) * X - (2/15) * X = (6/15) * X
But after spending for travel he is left with Rs. 100/- So
(6/15) * X = 100
X = 250
Brain Teaser No : 00128
There is a perfect sphere of diameter 40 cms. resting up against a perfectly straight wall and a
perfectly straight floor i.e. the wall and the floor make a perfect right angle.
Can a perfect sphere of diameter 7 cms. pass through the space between the big sphere, the wall
and the floor? Support your answer with valid arguments. Don't submit just "Yes" or "No".
Answer
For the sake of simplicity, consider two-dimension i.e view sphere as a two dimensional circle with diameter 40 cms.
From Figure I, (40 cms diameter sphere)
OC2 = OD2 + CD2
OC2 = 202 + 202
OC = 28.28427 cms
Also, X is the closest point to origin O on the sphere.
CX = 20 cms (radius)
OX = OC - CX
OX = 28.28427 - 20
OX = 8.28427 cms
From Figure II, (7 cms diameter sphere)
OP2 = OQ2 + PQ2
OP2 = (3.5)2 + (3.5)2
OP = 4.94974 cms
Also, Y is the farthest point to origin O on the sphere.
PY = 3.5 cms (radius)
OY = OP + PY
OY = 4.94974 + 3.5
OY = 8.44974 cms
Now, as OY > OX i.e. smaller sphere requires more space than the space available. Hence, smaller sphere of 7 cms diameter
can not pass through the space between the big sphere, the wall and the floor.
The puzzle can be solved by another method.
Draw a line tangent to the big sphere at the point X such that X is the closest point to the origin O on sphere. The tanget will cut
X and Y axes at A and B respectively such that OA=OB. [See Fig III] From above, OX=8.28427 cms.
From the right angle triangle OAB, we can deduct that
OA = OB = 11.71572 cms
AB = 16.56854 cms
Now, the diameter of the inscribed circle of right angle triangle is given by d = a + b - c where a <= b < c
The maximum possible diameter of the circle which can pass through the space between the big sphere, the wall and the floor
is
= OA + OB - AB
= 11.71572 + 11.71572 - 16.56854
= 6.86291 cms
Hence, the sphere with 7 cms diameter can not pass through the space between the big sphere, the wall and the floor.
Brain Teaser No : 00130
Bob's mom had three children Penny, Nickel and who was the third one?
Submitted by : whitney dunlap
Answer
Bob
Brain Teaser No : 00131
If a rooster is on top of a house and the rooster lays an egg which way will the egg fall down the house.
Submitted by : whitney dunlap
Answer
Neither. Roosters don't lay eggs.
Brain Teaser No : 00132
If a plane crashes on the border of Mexico and New Mexico, where will they bury the survivors?
Submitted by : whitney dunlap
Answer
Nowhere. You don't bury survivors !!!
Brain Teaser No : 00134
What is greater then GOD, worse then devil, dead men eat it and live men will die if they eat it?
Submitted by : ken
Answer
The answer is "NOTHING"
NOTHING is greater then god. NOTHING is worse then the devil, dead men eat NOTHING and if men eat NOTHING, they die.
Similar riddle:
What lasts forever, but if you eat it you will die?
Brain Teaser No : 00135
What can you put into a barrel but you cannot take out? When you put it in it makes the barrel lighter.
Submitted by : Lancer 2006
Answer
A Hole !!!
Brain Teaser No : 00136
What are the next two numbers in the series?
34, 58, 56, 60, 42, 52, 65, ?, ?
Answer
The next two numbers are 49 and 42.
The pattern is : the totals of the letters in the words ONE, TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT and NINE when
A=1, B=2, C=3, D=4 and so on.
First number = 15(O) + 14(N) + 5(E) = 34
Second Number = 20(T) + 23(W) + 15(O) = 58
Third Number = 20(T) + 8(H) + 18(R) + 5(E) + 5(E) = 56
Fourth Number = 6(F) + 15(O) + 21(U) + 18(R) = 60
Fifth Number = 6(F) + 9(I) + 22(V) + 5(E) = 42
Sixth Number = 19(S) + 9(I) + 24(X) = 52
Seventh Number = 19(S) + 5(E) + 22(V) + 5(E) + 14(N) = 65
Eight Number = 5(E) + 9(I) + 7(G) + 8(H) + 20(T) = 49
Ninth Number = 14(N) + 9(I) + 14(N) + 5(E) = 42
Brain Teaser No : 00137
It is raining outside and a man decides to take a walk. He goes outside with nothing but his shirt on his back, jeans on his legs and
shoes on his feet, yet not one hair on his head gets wet. Why is that?
Submitted by : Castill Hightower
Answer
The man is bald. As there are no hair on his head, no hair gets wet.
Brain Teaser No : 00138
There is a man who is looking at a picture. He is the only son in the family and his dad has no siblings.
He says, "This person's father is my father's son".
Who is this person in the picture?
Submitted by : Julie Nguyen
Answer
The person in the picture is his CHILD.
He is saying that "this person's father, is my father's son." Now, my father's son is himself as he is the only son in the family.
And he is the father of the person in picture. Hence the person in picture is his son or daughter.
Brain Teaser No : 00139
There was a man who had just hung himself. When you search the room where it happend all you can see is the young man
hanging and a puddle of water below him. There are no objects or furniture that could have helped him to commit suicide.
How did he kill himself?
Submitted by : beka chesse
Answer
The man stood on a block of ice. When it melted, he hung himself or he jumped off and hung himself.
Brain Teaser No : 00141
Before Mount Everest was discovered, what was the largest mountain above water on Earth ?
Submitted by : kukuchuboo
Answer
Mount Everest
Mount Everest was the largest mountain above water on the Earth before it was discovered. People just didn't know that it
existed.
Brain Teaser No : 00142
There are four groups of Mangoes, Apples and Bananas as follows:
Group I : 1 Mango, 1 Apples and 1 Banana
Group II : 1 Mango, 5 Apples and 7 Bananas
Group III : 1 Mango, 7 Apples and 10 Bananas
Group IV : 9 Mango, 23 Apples and 30 Bananas
Group II costs Rs 300 and Group III costs Rs 390.
Can you tell how much does Group I and Group IV cost?
Answer
Group I costs Rs 120 and Group IV costs Rs 1710
Assume that the values of one mango, one apple and one banana are M, A and B respectively.
From Group II : M + 5A + 7B = 300
From Group III : M + 7A + 10B = 390
Subtracting above to equations : 2A + 3B = 90
For Group I :
= M + A + B
= (M + 5A + 7B) - (4A + 6B)
= (M + 5A + 7B) - 2(2A + 3B)
= 300 - 2(90)
= 300 - 180
= 120
Similarly, for Group IV :
= 9M + 23A + 30B
= 9(M + 5A + 7B) - (22A + 33B)
= 9(M + 5A + 7B) - 11(2A + 3B)
= 9(300) - 11(90)
= 2700 - 990
= 1710
Thus, Group I costs Rs 120 and Group IV costs Rs 1710.
Brain Teaser No : 00144
There are 3 colored boxes - Red, Green and Blue. Each box contains 2 envelopes. Each envelope contains money - two of them
contain Rs. 25000 each, two of them contain Rs. 15000 each and remaining two contain Rs. 10000 each.
There is one statement written on the cover of each box.
* Red Box: Both, a red box and a blue box contain Rs. 10000 each.
* Green Box: Both, a green box and a red box contain Rs. 25000 each.
* Blue Box: Both, a blue box and a green box contain Rs. 15000 each.
Only one of the above 3 statements is true and the corresponding box contains the maximum amount.
Can you tell which box contains the maximum amount and how much?
Answer
Blue box contains the maximum amount Rs. 40000
As it is given that only one of the given 3 statements is true; assume in turn, each statement to be true & the other 2 false and
check whether the corresponding box contains the maximum amount.
Let's assume that the statement on the Blue box is true. Thus, the given 3 statements can be interpreted as
* Atmost one, a red box or a blue box contains Rs. 10000.
* Atmost one, a green box or a red box contains Rs. 25000.
* Both, a blue box and a green box contain Rs. 15000 each.
Going through all possible combinations, we can conclude that
Red Box : Rs. 10000 + Rs. 25000 = Rs. 35000
Green Box : Rs. 10000 + Rs. 15000 = Rs. 25000
Blue Box : Rs. 15000 + Rs. 25000 = Rs. 40000
You can test out for other two statements i.e. assuming Red box statement true and then Green box statement true. In both the
cases, other statements will contradict the true statement.
Brain Teaser No : 00145
A Father asks his son to go shopping for apples one day. He gives his son exactly 100 pence and instructs that he must spend all
of it and buy exactly 100 apples from the market.
The market sells three kinds of apples. Good apples are priced at 10 pence, Average apples at 5 pence and Rotten apples at 0.5
pence.
It does not matter what type of apples the boy buys. How many of each apple must the boy buy in order to fulfil his father's
instructions.
Submitted by : Vincent Kamal Murray
Answer
Assume that the son will buy total of X apples of 10 pence each, Y apples of 5 pence each and Z apples of 0.5 pence each.
As the son must buy 100 apples,
X + Y + Z = 100 ----------I
Also, the total price must be 100 pence,
10 * X + 5 * Y + 0.5 * Z = 100
20 * X + 10 * Y + Z = 200 ----------II
Subtracting equation I from equation II,
19 * X + 9 * Y = 100
It is obvious that values of X, Y and Z are integers. So using trial and error, X = 1 and Y = 9
Using values of X and Y, Z = 90
1 Good apple = 10 pence
9 Average apple = 45 pence
90 rotten apples = 45 pence
Hence, total of 100 apples for 100 pence.
Brain Teaser No : 00146
Sachin, Dravid and Ganguly played in a Cricket match between India and England.
• None of them scored more than 99 runs.
• If you add the digits of the runs scored by Sachin to his own score, you will get the runs scored by Dravid.
• If you reverse the digits of the runs scored by Dravid, you will get the runs scored by Ganguly.
• The total runs scored by them is 240.
Can you figure out their individual scores?
Answer
Sachin, Dravid and Ganguly scored 75, 87 and 78 respectively.
Sachin's score must be less than 86, otherwise Dravid's score would be more than 99. Also, he must have scored atleast 42 -
incase Dravid and Ganguly scored 99 each.
Also, as none of them scored more than 99 and the total runs scored by them is 240; their individual scores must be around 80.
Now, use trial-n-error method to solve the teaser.
Brain Teaser No : 00147
Jack and Jill were found dead one morning on the floor of a room. Neither had any scratches or bruises on their bodies, but their is
broken glass and water all around them.
No chemicals or poisons are in their bodies. The only other thing in the room is a table.
How did Jack and Jill die?
Submitted by : Kirsten
Answer
Jack and Jill were fish. Their fishbowl fell off the table and they died because of lack of water. 0;-)
Brain Teaser No : 00148
A man comes into town on Friday and leaves three days later on Friday.
How does he do it?
Submitted by : Michaela
Answer
The man's horse name is Friday and he left the town on horse. So left on Friday. 0;-)
Brain Teaser No : 00149
As I was traveling to St.Petersberg I saw a man with 7 wives, with 7 kittens, in 7 sacks, and with 7 drinks on a bike.
How many people/things are going to St. Petersberg?
Submitted by : Mark b
Answer
One man is traveling to St. Petersberg.
It said as I saw a man with 7 wives, with 7 kittens, in 7 sacks, and with 7 drinks, on a bike. He only saw them, so they didnot
count. Hence, he is the only person that is actually going.
Teaser No : 00151
Assume that you have enough coins of 1, 5, 10, 25 and 50 cents.
How many ways are there to make change for a dollar? Do explain your answer.
Answer
There are 292 ways to make change for a dollar using coins of 1, 5, 10, 25 and 50 cents.
Let's generalised the teaser and make a table as shown above.
If you wish to make change for 75 cents using only 1, 5, 10 and 25 cent coins, go to the .25 row and the 75 column to obtain
121 ways to do this.
The table can be created from left-to-right and top-to-bottom. Start with the top left i.e. 1 cent row. There is exactly one way to
make change for every amount. Then calculate the 5 cents row by adding the number of ways to make change for the amount
using 1 cent coins plus the number of ways to make change for 5 cents less using 1 and 5 cent coins.
Let's take an example:
To get change for 50 cents using 1, 5 and 10 cent coins.
* 50 cents change using 1 and 5 cent coins = 11 ways
* (50-10) 40 cents change using 1, 5 and 10 cent coins = 25 ways
* 50 cents change using 1, 5 and 10 cent coins = 11+25 = 36 ways
Let's take another example:
To get change for 75 cents using all coins up to 50 cent i.e. 1, 5, 10, 25 and 50 cents coins.
* 75 cents change using coins upto 25 cent = 121 ways
* (75-50) 25 cents change using coins upto 50 cent = 13 ways
* 75 cents change using coins upto 50 cent = 121+13 = 134 ways
For people who don't want to tease their brain and love to do computer programming, there is a simple way. Write a small multiloop
program to solve the equation: A + 5B + 10C + 25D + 50E = 100
where,
A = 0 to 100
B = 0 to 20
C = 0 to 10
D = 0 to 4
E = 0 to 2
The program should output all the possible values of A, B, C, D and E for which the equation is satisfied.
Brain Teaser No : 00152
There is a river and 3 people. Two people weigh 50 lbs and one of them weighs 100 lbs. The only way you can cross the river is by
using a boat.
How can they all cross the river if the boat only can hold 100 lbs?
Submitted by : BeCkA
Answer
1. Both 50 pound persons will cross the river.
2. One of the 50 pound person will come back.
3. Now, 100 pound person will cross the river alone.
4. 50 pound person will come back who is at the other end of the river.
5. Again both 50 pound persons will cross the river together.
Brain Teaser No : 00153
In a Road Race, one of the three bikers was doing 15km less than the first and 3km more than the third. He also finished the race
12 minutes after the first and 3 minutes before the third.
Can you find out the speed of each biker, the time taken by each biker to finish the race and the length of the course?
Assume that there were no stops in the race and also they were driving with constant speeds through out the race.
Answer
Let us assume that
Speed of First biker = V1 km/min
Speed of Second biker = V2 km/min
Speed of Third biker = V3 km/min
Total time take by first biker = T1 min
Total distance = S km
Now as per the data given in the teaser, at a time T min
X1 = V1 * T ----> 1
X1 - 15 = V2 * T ----> 2
X1 - 18 = V3 * T ----> 3
At a Distance S Km.
S = V1 * T1 ----> 4
S = V2 * (T1 + 12) ----> 5
S = V3 * (T1 + 15) ----> 6
Thus there are 6 equations and 7 unknown data that means it has infinite number of solutions.
By solving above 6 equations we get,
Time taken by first biker, T1 = 60 Min.
Time taken by Second biker, T2 = 72 Min.
Time taken by first biker, T3 = 75 Min.
Also, we get
Speed of first biker, V1 = 90/T km/min
Speed of second biker, V2 = (5/6)V1 = 75/T km/min
Speed of third biker, V3 = (4/5)V1 = 72/T km/min
Also, the length of the course, S = 5400/T km
Thus, for the data given, only the time taken by each biker can be found i.e. 60, 72 and 75 minutes. For other quantities, one
more independent datum is required i.e. either T or V1 or V2 or V3
Thanks to Theertham Srinivas for the answer !!!
Brain Teaser No : 00154
There are 4 mugs placed upturned on the table. Each mug have the same number of marbles and a statement about the number of
marbles in it. The statements are: Two or Three, One or Four, Three or One, One or Two.
Only one of the statement is correct. How many marbles are there under each mug?
Answer
A simple one.
As it is given that only one of the four statement is correct, the correct number can not appear in more than one statement. If it
appears in more than one statement, then more than one statement will be correct.
Hence, there are 4 marbles under each mug.
Brain Teaser No : 00155
Which is heavier a pound of bricks or a pound of feathers?
Submitted by : Priscilla M
Answer
Both of them weigh one pound. So neither is heavier than the other, both are same.
Note
The pound is the name for at least three different units of mass: the pound (avoirdupois), the troy pound, and the obsolete
imperial pound.
Gold is measured in "troy" pounds which is lighter
than "Avoirdupois" pounds which is most commonly used. "Imperial" units are still predominantly used in the United States.
So if a pound of gold is measured in troy pounds and feathers in Avoirdupois pounds, then gold is lighter.
Brain Teaser No : 00156
The game of Tic-Tac-Toe is being played between two players. Only the last mark to be placed in the game as shown.
Who will win the game, O or X? Can you tell which was the sixth mark and at which position? Do explain your answer.
Assume that both the players are intelligent enough.
Answer
O will win the game. The sixth mark was X in square 9.
The 7th mark must be placed in square 5 which is the win situation for both X and O. Hence, the 6th mark must be placed in a
line already containing two of the opponents marks. There are two such possibilities - the 6th mark would have been either O in
square 7 or X in square 9.
As we know both the players are intelligent enough, the 6th mark could not be O in square 7. Instead, he would have placed O
in square 5 and would have won.
Hence, the sixth mark must be X placed in square 9. And the seventh mark will be O. Thus O will win the game.
Brain Teaser No : 00158
Consider the sum: ABC + DEF + GHI = JJJ
If different letters represent different digits, and there are no leading zeros, what does J represent?
Answer
The value of J must be 9.
Since there are no leading zeros, J must be 7, 8, or 9. (JJJ = ABC + DEF + GHI = 14? + 25? + 36? = 7??)
Now, the remainder left after dividing any number by 9 is the same as the remainder left after dividing the sum of the digits of
that number by 9. Also, note that 0 + 1 + ... + 9 has a remainder of 0 after dividing by 9 and JJJ has a remainder of 0, 3, or 6.
The number 9 is the only number from 7, 8 and 9 that leaves a remainder of 0, 3, or 6 if you remove it from the sum 0 + 1 + ... +
9. Hence, it follows that J must be 9.
Brain Teaser No : 00159
Each of the five characters in the word BRAIN has a different value between 0 and 9. Using the given grid, can you find out the
value of each character?
B R A I N 31
B B R B A 31
N I A B B 32
N I B A I 30
I R A A A 23
37 29 25 27 29
The numbers on the extreme right represent the sum of the values represented by the characters in that row. Also, the numbers on
the last raw represent the sum of the values represented by the characters in that column. e.g. B + R + A + I + N = 31 (from first
row)
Answer
B=7, R=6, A=4, I=5 and N=9
Make total 10 equations - 5 for rows and 5 for columns - and sovle them.
From Row3 and Row4,
N + I + A + B + B = N + I + B + A + I + 2
B = I + 2
From Row1 and Row3,
B + R + A + I + N = N + I + A + B + B - 1
R = B - 1
From Column2,
R + B + I + I + R = 29
B + 2R + 2I = 29
B + 2(B - 1) + 2I = 29
3B + 2I = 31
3(I + 2) + 2I = 31
5I = 25
I = 5
Hence, B=7 and R=6
From Row2,
B + B + R + B + A = 31
3B + R + A = 31
3(7) + 6 + A = 31
A = 4
From Row1,
B + R + A + I + N = 31
7 + 6 + 4 + 5 + N = 31
N = 9
Thus, B=7, R=6, A=4, I=5 and N=9
Brain Teaser No : 00160
A family photo contained:
one grandfather, one grandmother;
two fathers, two mothers;
six children, four grandchildren;
two brothers, two sisters;
three sons, three daughters;
one father-in-law, one mother-in-law, one daughter-in-law, one son-in-law
30 people you may think, but no, what is the least number of people here?
Answer
There are total 8 people.
Four children - 2 boys and 2 girls, their mother and father, and one set of grandparents - EITHER mother's mother and father's
father OR mother's father and father's mother.
Brain Teaser No : 00162
At the Party:
1. There were 9 men and children.
2. There were 2 more women than children.
3. The number of different man-woman couples possible was 24. Note that if there were 7 men and 5 women, then there
would have been 35 man-woman couples possible.
Also, of the three groups - men, women and children - at the party:
4. There were 4 of one group.
5. There were 6 of one group.
6. There were 8 of one group.
Exactly one of the above 6 statements is false.
Can you tell which one is false? Also, how many men, women and children are there at the party?
Answer
Statement (4) is false. There are 3 men, 8 women and 6 children.
Assume that Statements (4), (5) and (6) are all true. Then, Statement (1) is false. But then Statement (2) and (3) both can not
be true. Thus, contradictory to the fact that exactly one statement is false.
So Statement (4) or Statement (5) or Statement (6) is false. Also, Statements (1), (2) and (3) all are true.
From (1) and (2), there are 11 men and women. Then from (3), there are 2 possible cases - either there are 8 men and 3
women or there are 3 men and 8 women.
If there are 8 men and 3 women, then there is 1 child. Then Statements (4) and (5) both are false, which is not possible.
Hence, there are 3 men, 8 women and 6 children. Statement (4) is false.
Brain Teaser No : 00163
What belongs to you, but is almost entirely used by other people?
Submitted by : HappyGirl
Answer
Your Name
Your Name belongs to you, but is almost entirely used by others in day-to-day life.
Brain Teaser No : 00164
Substitute digits for the letters to make the following relation true.
W O R L D
+ T R A D E
-------------
C E N T E R
Note that the leftmost letter can't be zero in any word. Also, there must be a one-to-one mapping between digits and letters. e.g. if
you substitute 3 for the letter W, no other letter can be 3 and all other W in the puzzle must be 3.
Answer
A tough one.
It is obvious that C=1. Also, the maximum possible value of E is 7. Now, start putting possible values of D, E and R as they
occure frequently and use trial-n-error.
W O R L D 5 3 6 8 4
+ T R A D E + 7 6 0 4 2
------------ ------------
C E N T E R 1 2 9 7 2 6
Brain Teaser No : 00165
A fish had a tail as long as its head plus a quarter the lenght of its body. Its body was three-quarters of its total length. Its head was
4 inches long.
What was the length of the fish?
Submitted by : Calon
Answer
The fish is 128 inches long.
It is obvious that the lenght of the fish is the summation of lenghts of the head, the body and the tail. Hence,
Fish (F) = Head (H) + Body (B) + Tail (T)
But it is given that the lenght of the head is 4 inches i.e. H = 4. The body is three-quarters of its total length i.e. B = (3/4)*F. And
the tail is its head plus a quarter the lenght of its body i.e. T = H + B/4. Thus, the equation is
F = H + B + T
F = 4 + (3/4)*F + H + B/4
F = 4 + (3/4)*F + 4 + (1/4)*(3/4)*F
F = 8 + (15/16)*F
(1/16)*F = 8
F = 128 inches
Thus, the fish is 128 inches long.
Brain Teaser No : 00166
I have holes in my top and bottom, my left and right, and in my middle. But I still hold water. What am I?
Answer
A Sponge
A Sponge is porous - has holes on all of its sides, but yet it absorbs and holds water.
Brain Teaser No : 00167
What are the chances that at least two out of a group of fifty people share the same birthday?
Submitted by : Erin
Answer
The probability of atleast two out of a group of 50 people share the same birthday is 97%
Probability of atleast two share the same birthday = 1 - probability of all 50 have different birthdays
Probability of all 50 have different birthday
= 365/365 * 364/365 * 363/365 * ... * 317/365 * 316/365
= (365 * 364 * 363 * 362 * ... * 317 * 316)/36550
= 0.0296264
Probability of atleast two share the same birthday
= 1 - 0.0296264
= 0.9703735
= 97% approx.
Thus, the probability of atleast two out of a group of 50 people share the same birthday is 97%
This explains why in a school/college with classrooms of 50 students, there are at least two students with a birthday on
the same day of the year. Also, if there are 23 people in the room, then there are 50% chances that atleast two of them have
a birthday on the same day of the year!!!
Brain Teaser No : 00168
Chintu put some Black marbles and some White marbles into a jar. He then asked his brother Pintu to take out a marble. Pintu
drew out a Black marble. Chintu asked Pintu to draw out another marble, and again he drew out a Black marble.
Pintu thought there must be more Black marbles than White marbles in the jar and asked Chintu, "I wonder what is the probability
of me drawing a Black marble on a third try?"
Chintu replied, "Exactly 9/10 of what it was of drawing a Black marble on your first draw."
Can you help Pintu to determine how many marbles of each colour had been in the jar in the beginning? Give the minimal possible
answer. Also, Pintu knew that there were at least seven marbles in the jar in the beginning.
Answer
There were 8 Black marbles and 4 White marbles in the jar.
Let's assume that initially there are total N marbles. Also, B and W are the number of Black and White marbles respectively.
Thus, N = B + W
The probability of drawing a Black marble on the first draw = B/(B+W)
Similarly, after drawing 2 Black marbles, the probability of drawing a Black marble on the third draw = (B-2)/(B+W-2)
Chintu said that the probability of drawing a Black marble on third draw (after drawing Black marbles on first two draws) is
exactly 9/10 of what it was of drawing a Black marble on first draw.
(B - 2) / (B + W - 2) = (9 / 10) * B / (B + W)
10 * (B + W) * (B - 2) = 9 * B * (B + W - 2)
10B2 - 20B + 10BW - 20W = 9B2 + 9BW - 18B
B2 - 2B + BW - 20W = 0
We know that N = B + W, hence substitute W = N - B
B2 - 2B + B(N - B) - 20(N - B) = 0
B2 - 2B + BN - B2 - 20N + 20B = 0
18B + BN - 20N = 0
B(18 + N) = 20N
B = 20N / (18 + N)
Now, we know that the value of N is at least 7. Hence, using trial-n-error on the equation, the minimal value of N must be 12 so
that B=8 and W=4.
Hence, initially there were 8 Black marbles and 4 White marbles in the jar.
Brain Teaser No : 00169
Pinto says, "The horse is not Black."
Sandy says, "The horse is either Brown or Grey."
Andy says, "The horse is Brown."
At least one is telling truth and at least one is lying.
Can you tell the color of the horse?
Answer
The color of the horse can be any color other than Black and Brown.
If the color of the horse is Black - all are lying.
If the color of the horse is Brown - all are telling truth.
Thus, the horse is neither Black nor Brown.
If the color of the horse is Grey - Pinto and Sandy are telling truth whereas Andy is lying.
If the color of the horse is other than Black, Brown and Grey - Pinto is telling truth whereas Sandy and Andy are lying.
You must have noticed that for the given conditions, Pinto is always telling truth whereas Andy is always lying.
Brain Teaser No : 00170
A series comprising of alphabets contains 13 letters. The first seven letters in the given series are A, E, F, H, I, L, M
Can you find the next two letters?
Answer
The next letters in the series are N, O, R, S, U, X.
The pattern is - letters whose English names (Phonetic Pronunciations) start with vowels.
Brain Teaser No : 00171
Two fathers and two sons go out hunting one day in a huge forest. At the end of the day, only three people emerge from the forest.
What happened? Note that not a single person is killed/death.
Submitted by : Vertu
Answer
There are only three person entered the forest. Son, Father and Grandfather.
• There are two fathers - the father and the grandfather. As grandfather is father's father.
• There are also two sons - the son and the father. As the father is the grandfathers son.
Brain Teaser No : 00172
If you were to spell out numbers (starting from 1) in English, how far would you have to go until you would find the letter "A"?
Answer
One Thousand
Brain Teaser No : 00173
Tom and Jerry and the boys in the bar were exchanging old war stories.
Tom offered one about how his grandfather led a battalion against a German division during World War I. Through brilliant
maneuvers, he defeated them and captured valuable territory. After the battle he was awarded a medal that was inscribed with:
"For Bravery, Daring and Leadership - World War I.
From the Men of Battalion 8."
Jerry looked at Tom and said, "You really don't expect anyone to believe that yarn, do you?"
What's wrong with the story?
Answer
World War I wasn't called "World War I" until World War II.
Brain Teaser No : 00174
Arrange five planets such that 4 of them add up to 5th planet numerically. Each of the letters of the planet should represent a
unique number from the range 0 - 9. You have to use all ten digits.
There is an amazing mathematical relationship exists among the names of the planet.
Answer
The tought process is initially to find planets such that the total number of alphabets in them is 10.
The only possible combination of planets is Saturn, Uranus, Venus, Mars and Neptune because for other combinations there
will be more than 10 alphabets. Among these five, Neptune is the lenghtiest, so it must be the sum of the other four.
S A T U R N
U R A N U S
V E N U S
+ M A R S
--------------
N E P T U N E
Now the only possible value for N is 1. By finding the value for S, we can reach the result:
3 5 8 6 9 1
6 9 5 1 6 3
2 0 1 6 3
+ 4 5 9 3
--------------
1 0 7 8 6 1 0
Brain Teaser No : 00175
A woman is about to be executed. Since she has been a good citizen most of her life, the executioner gives her the option of
chosing by which way she can die, no matter how bizarre, time-consuming, or costly it is.
What manner of death should she choose, or will it not make a difference?
Submitted by : Rachel Kalmin
Answer
She should choose 'an Old Age death' or 'a Natural death'.
Brain Teaser No : 00177
"Santa Express" is one kilometer long and always travels at the speed of 60 kilometers per hour.
It passes through a tunnel which is one kilometer long. How long the Express will take to pass completely through the tunnel?
Answer
The express will take total of 2 minutes to pass completely through the tunnel.
The speed of the Santa Express is 60 kms/hr i.e. one km per minute.
The engine of the Express will take one minute to reach from one end to the other end of the tunnel, as it travels at the speed of
one km per minute and the tunnel is one km long. Thus, after one minute, the Express will be completely inside the tunnel.
Now it will take another one minute to completely come out of the tunnel. Thus, the express will take total of 2 minutes to pass
completely through the tunnel.
Brain Teaser No : 00178
Vipul was studying for his examinations and the lights went off. It was around 1:00 AM. He lighted two uniform candles of equal
length but one thicker than the other. The thick candle is supposed to last six hours and the thin one two hours less. When he
finally went to sleep, the thick candle was twice as long as the thin one.
For how long did Vipul study in candle light?
Answer
Vipul studied for 3 hours in candle light.
Assume that the initial lenght of both the candle was L and Vipul studied for X hours.
In X hours, total thick candle burnt = XL/6
In X hours, total thin candle burnt = XL/4
After X hours, total thick candle remaining = L - XL/6
After X hours, total thin candle remaining = L - XL/4
Also, it is given that the thick candle was twice as long as the thin one when he finally went to sleep.
(L - XL/6) = 2(L - XL/4)
(6 - X)/6 = (4 - X)/2
(6 - X) = 3*(4 - X)
6 - X = 12 - 3X
2X = 6
X = 3
Hence, Vipul studied for 3 hours i.e. 180 minutes in candle light.
Brain Teaser No : 00179
I bet you Rs. 100 that if you give me Rs. 200, I will give you Rs. 300 in return.
Would you bet with me? Why?
Answer
No, you should not bet.
Let's say you bet and you gave Rs. 200 to me. Now there are 2 possibilities.
CASE I - I will give you Rs. 300
If I give you Rs. 300, then I will win Rs. 100 bet. Thus, you have to give me Rs. 100. This is NO WIN NO LOSE case.
CASE II - I won't give you Rs. 300
If I won't give you Rs. 300, then I will lose Rs. 100 bet. Thus, I have to give you Rs. 100 which I will give you with smile :-) (of
course, from Rs. 200 you gave me initially) Here, I will make Rs. 100 and you will lose Rs. 100
So the moral - you should not bet !!!
Brain Teaser No : 00180
Which number in the series does not fit in the given series:
1 4 3 16 6 36 7 64 9 100
Answer
This is a series with odd positions containing position number whereas even positions containing square of the position.i.e.
even position numbers are 4 16 36 64 100 and odd position numbers are 1 3 5 7 9
Hence, 6 does not fit in the series. It should be 5.
Brain Teaser No : 00181
How do you cut a square cake into 8 equal piece only using 3 straight cuts?
Note that you can not move the pieces as you cut the cake.
Submitted by : Danny Klein
Answer
Cut cake into 4 quarters by 2 vertical cuts which are perpendicular to each other. Now slice the cake horizontially which makes
total 8 pieces.
Brain Teaser No : 00182
Subhash is 14 inches taller than Jatin. The difference between Subhash and Sanjeev is two inches less than between Sanjeev and
Jatin. Subhash at 6'6" is the tallest.
How tall are Sanjeev and Jatin?
Answer
Sanjeev is 6' and Jatin is 5'4"
It is given that Subhash at 6'6" is the tallest and also he is 14 inches taller than Jatin. It means that Jatin is 5'4".
Now as the difference between Subhash and Sanjeev is two inches less than between Sanjeev and Jatin, Sanjeev's height is
more than Jatin's. And that is 6'.
Thus, Sanjeev is 6' and Jatin is 5'4".
Brain Teaser No : 00183
Thirty white horses on a red hill,
First they champ,
Then they stamp,
Then they stand still.
Answer
Teeth
Thirty white horses are the teeth
A red hill is the gum
First they champ i.e. munch or bite the food
Then they stamp i.e. crush the food
Then they stand still i.e. do nothing as food is eaten
Brain Teaser No : 00184
Of the 120 people in the room, 3/5 are women. If 2/3 of the people are married, what is the maximum number of women in the room
who could be unmarried?
Answer
Maximum 40 women are unmarried.
In the room , there are (3/5)*120 = 72 Women and hence, 48 Men.
Also, married people are (2/3)*120 = 80 which means that 40 people are unmarried.
Even assuming all of the men are married, this still leaves 80 - 48 = 32 others who are married, and those other are women. So
atleast 32 women must be married, which means that maximum possible number of women who are unmaried is 72 - 32 = 40
Brain Teaser No : 00185
Two trains starting at same time, one from Bangalore to Mysore and other in opposite direction arrive at their destination 1hr and
4hrs respectively after passing each other.
How much faster is one train from other?
Answer
The speed of Bangalore-Mysore train is TWICE the speed of Mysore-Bangalore train.
Let the distance between Bangalore and Mysore is D kms.
Also, let speed of the train from Bangalore to Mysore is X km/hr and speed of the tain from Mysore to Bangalore is Y km/hr.
Now, assume that both the trains met each other at T kms from the Bangalore (point P in figure)
Time taken by Bangalore-Mysore train to reach P = Time taken by Mysore-Bangalore train to reach P
( T / X ) = ( D - T ) / Y -----equ(I)
Also, Bangalore-Mysore train and Mysore-Bangalore train arrive destination 1 hr and 4 hrs respectively after passing each
other. It means that Bangalore-Mysore train travels (D - T) kms in 1 hr at X km/hr and Mysore-Bangalore train travels T kms in
4 hrs at Y km/hr. Hence,
( D - T ) = X and
T = 4 * Y
Substituting these values in equation I, we get
( 4 * Y ) / X = X / Y
4 * Y * Y = X * X
2 * Y = X
Hence, the speed of Bangalore-Mysore train is TWICE the speed of Mysore-Bangalore train.
Brain Teaser No : 00186
500 men are arranged in an array of 10 rows and 50 columns according to their heights.
Tallest among each row of all are asked to come out. And the shortest among them is A.
Similarly after resuming them to their original positions, the shortest among each column are asked to come out. And the tallest
among them is B.
Now who is taller A or B ?
Answer
No one is taller, both are same as A and B are the same person.
As it is mentioned that 500 men are arranged in an array of 10 rows and 50 columns according to their heights. Let's assume
that position numbers represent their heights. Hence, the shortest among the 50, 100, 150, ... 450, 500 is person with height 50
i.e. A. Similarly the tallest among 1, 2, 3, 4, 5, ..... 48, 48, 50 is person with height 50 i.e. B
Now, both A and B are the person with height 50. Hence both are same.
Brain Teaser No : 00187
There is a safe with a 5 digit number as the key. The 4th digit is 4 greater than the second digit, while the 3rd digit is 3 less than the
2nd digit. The 1st digit is thrice the last digit. There are 3 pairs whose sum is 11.
Find the number.
Answer
65292
As per given conditions, there are three possible combinations for 2nd, 3rd and 4th digits. They are (3, 0, 7) or (4, 1, 8) or (5, 2,
9)
It is given that there are 3 pairs whose sum is 11. All possible pairs are (2, 9), (3, 8), (4, 7), (5, 6). Now required number is 5
digit number and it contains 3 pairs of 11. So it must not be having 0 and 1 in it. Hence, the only possible combination for 2nd,
3rd and 4th digits is (5, 2, 9)
Also, 1st digit is thrice the last digit. The possible combinations are (3, 1), (6, 2) and (9, 3), out of which only (6, 2) with (5, 2, 9)
gives 3 pairs of 11. Hence, the answer is 65292.
Brain Teaser No : 00188
What letter comes next in the series:
O, T, T, F, F, S, S, E, N, _?
Submitted by : Rachel Kalmin
Answer
T
The letters are the first letters of the numbers starting at One and they stand for the first ten numbers i.e. One, Two, Three,
Four, Five, Six, Seven, Eight, Nine, Ten
Brain Teaser No : 00189
A man walked one mile south. Then he walked one mile east. Then he walked one mile north. He realized he was exactly where he
started. Just then, he was attacked by a bear.
What color was the bear?
Submitted by : Rachel Kalmin
Answer
White - a polar bear.
The man travels one mile south(down), one mile east(right), and one mile north(up) - a square with the top side missing is
made. If he ended where he started, the shape has to form a triangle. The only place on earth that can have three equal
distances travelled, each at a nintey degree angle, is if you start at the north pole. And only polar bears live that far north, so
the bear is white.
Brain Teaser No : 00190
We have to fill number from 1 to 12 at the intersection point of two or more lines. We have to construct a star using
two triangle. The sum of all number lying in straight lines should be same. This can be easilty understood by the fig.
and hence solved.
Submitted by : Vaibhav Gupta
Answer
We have one answer where sum of all the numbers lying in straight lines is 26.
If you have others, do submit them.
Brain Teaser No : 00193
If one person sends the e-mail to two friends, asking each of them to copy the mail and send it to two of their friends, those in turn
send it to two of their friends and so on.
How many e-mails would have been sent by the time it did 30 sets?
Answer
2147483646
First person sent the mail to 2 persons. Those 2 sent the mail to 2 persons each, total 4 persons. Now, those 4 person sent
mail to total 8 persons, then 8 to 16 persons, 16 to 32 persons and so on.... Hence, it a series of 2, 4, 8, 16, 32 upto 30
numbers
It is a Geometric series with common ratio 2 and first number is also 2. Summation of such series is given by A * (Rn - 1) / (R -
1) where
A = First term
R = Common Ratio
n = total numbers
So total number of times mail sent by the time it did 30 sets
= 2 * (230 - 1) / (2 - 1)
= 2 * (1073741824 - 1)
= 2 * 1073741823
= 2147483646
Brain Teaser No : 00195
A camp-fire was attended by 49 friends. After shaking hands, each of them sat on the round table and clinked their mug with the
friends to his immediate left and immediate right.
How many times did the mugs clink?
Answer
49 times
Let's assume that everyone clinked their mug with friend to his left only. It means that there are total 49 clinks. Now the right
clink of each person is left clink of the person on right which is already happened. Hence, there are only 49 clinks.
Brain Teaser No : 00196
Veeru says to Jay, "Can you figure out how many Eggs I have in my bucket?" He gives 3 clues to Jay: If the number of Eggs I have
1. is a multiple of 5, it is a number between 1 and 19
2. is not a multiple of 8, it is a number between 20 and 29
3. is not a multiple of 10, it is a number between 30 and 39
How many Eggs does Veeru have in his bucket?
Answer
32 eggs
Let's apply all 3 condition separately and put all possible numbers together.
First condition says that if multiple of 5, then the number is between 1 and 19. Hence, the possible numbers are (5, 10, 15, 21,
22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
Second condition says that if not a multiple of 8, then the number is between 20 and 29. Hence, the possible numbers are (8,
16, 20, 21, 22, 23, 25, 26, 27, 28, 29, 32)
Third condition says that if not a multiple of 10, then the number is between 30 and 39. Hence, the possible numbers are (10,
20, 31, 32, 33, 34, 35, 36, 37, 38, 39)
Only number 32 is there in all 3 result sets. That means that only number 32 satisfies all three conditions. Hence, Veeru have
32 eggs in his bucket.
Brain Teaser No : 00197
There are 70 employees working with BrainVista of which 30 are females. Also,
• 30 employees are married
• 24 employees are above 25 years of age
• 19 married employees are above 25 years, of which 7 are males
• 12 males are above 25 years of age
• 15 males are married.
How many unmarried females are there and how many of them are above 25?
Answer
15 unmarried females & none are above 25 years of age.
Simply put all given information into the table structure and you will get the answer.
Married Unmarried
Below 25 Above 25 Below 25 Above 25
Female 3 12 15 0
Male 8 7 20 5
Brain Teaser No : 00198
Once a week a wagon driver leaves his hut and drives his wagon to the river dock to pick up supplies for his town. At 4:05 PM, onefifth
of the way to the dock, he passes the Temple. At 4:15 PM, one-third of the way, he passes the Preetam-Da-Dhabaa.
At what time does he reached the dock?
Answer
5:05 PM
At 4:05 PM, the wagon driver passes the temple, one-fifth of the way to the dock. Also, at 4:15 PM, he passes the Preetam-Da-
Dhabaa, one-third of the way. Thus, he travels 2/15 (1/3 - 1/5) of the distance in 10 minutes.
At 4:15 PM, he has already travelled 1/3 of the distance. Thus 2/3 of the way is remaining, which can be travelled in
= ( (2/3) * 10 ) / (2/15)
= 50 minutes
At 4:15, he was at Preetam-Da-Dhabaa.and remaining way will take 50 more minutes. Hence, the driver will reach at 5:05 PM
to the dock.
Brain Teaser No : 00199
Raj has a jewel chest containing Rings, Pins and Ear-rings. The chest contains 26 pieces. Raj has 2 1/2 times as many rings as
pins, and the number of pairs of earrings is 4 less than the number of rings.
How many earrings does Raj have?
Answer
12 earrings
Assume that there are R rings, P pins and E pair of ear-rings.
It is given that, he has 2 1/2 times as many rings as pins.
R = (5/2) * P or P = (2*R)/5
And, the number of pairs of earrings is 4 less than the number of rings.
E = R - 4 or R = E + 4
Also, there are total 26 pieces.
R + P + 2*E = 26
R + (2*R)/5 + 2*E = 26
5*R + 2*R + 10*E = 130
7*R + 10*E = 130
7*(E + 4) + 10*E = 130
7*E + 28 + 10*E = 130
17*E = 102
E = 6
Hence, there are 6 pairs of Ear-rings i.e. total 12 Ear-rings
Brain Teaser No : 00200
An apple vendor has 1000 apples and 10 empty boxes. He asks his son to place all the 1000 apples in all the 10 boxes in such a
manner that if he asks for any number of apples from 1 to 1000, his son should be able to pick them in terms of boxes.
How did the son place all the apples among the 10 boxes, given that any number of apples can be put in one box.
Answer
1, 2, 4, 8, 16, 32, 64, 128, 256, 489
Let's start from scratch.
• The apple vandor can ask for only 1 apple, so one box must contain 1 apple.
• He can ask for 2 apples, so one box must contain 2 apples.
He can ask for 3 apples, in that case box one and box two will add up to 3.
• He can ask for 4 apples, so one box i.e. third box must contain 4 apples.
• Now using box number one, two and three containing 1, 2 and 4 apples respectively, his son can give upto 7 apples.
Hence, forth box must contain 8 apples.
• Similarly, using first four boxes containing 1, 2, 4 and 8 apples, his son can give upto 15 apples. Hence fifth box must
contain 16 apples.
• You must have noticed one thing till now that each box till now contains power of 2 apples. Hence the answer is 1, 2,
4, 8, 16, 32, 64, 128, 256, 489. This is true for any number of apples, here in our case only upto 1000.
Brain Teaser No : 00202
Weight in my belly,
Trees on my back,
Nails in my ribs,
Feet I do lack.
Who or what am I?
Submitted by : Dave
Answer
A Ship or a Boat
The Cargo is the weight in his belly.
Trees on his back are the Planks used.
Nails are used to fix the planks together.
Ship/Boat do not have feet.
Brain Teaser No : 00203
Do you know the missing number in the given series?
10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, ___ , 100, 121, 10000
Answer
The missing number is 31.
The pattern is - Sixteen in the base n for n = 16, 15, ..., 2.
16 in the base 16 = 10
16 in the base 15 = 11
16 in the base 14 = 12
16 in the base 13 = 13
16 in the base 12 = 14
16 in the base 11 = 15
16 in the base 10 = 16
16 in the base 9 = 17
16 in the base 8 = 20
16 in the base 7 = 22
16 in the base 6 = 24
16 in the base 5 = 31
16 in the base 4 = 100
16 in the base 3 = 121
16 in the base 2 = 10000
Thus, the complete series is - 10, 11, 12, 13, 14, 15, 16, 17, 20, 22, 24, 31, 100, 121, 10000
Brain Teaser No : 00204
It cannot be seen, cannot be felt
Cannot be heard, cannot be smelt
It lies behind stars and under hills
And empty holes it fills
It comes first and follows after
Ends life, kills laughter.
Answer
The darkness (The dark)
The darkness cannot be seen, cannot be felt, cannot be heard, cannot be smelt. There is darkness behind stars and under
hills. Also, there is darkness in empty holes.
Brain Teaser No : 00205
Which is correct:
A> The Second Millennium began on Jan 1, 2000
B> The Second Millennium will begin on Jan 1, 2001
Answer
Neither is correct.
The second millennium began January 1, 1001.
Brain Teaser No : 00206
A tank can be filled by pipe A in 30 minutes and by pipe B in 24 minutes. Outlet pipe C can empty the full tank in one hour and
twenty minutes.
If the tank is empty initially and if all the three pipes A, B and C are opened simultaneously, in how much time will the tank be full?
Answer
The tank will be full in 16 minutes.
In one minute,
pipe A can fill 1/30 part of the tank.
pipe B can fill 1/24 part of the tank.
pipe C can empty 1/80 part of the tank.
Thus, the net water level in one minute is
= 1/30 + 1/24 - 1/80
= 15/240 part of the tank
Hence, the tank will be full in 240/15 i.e. 16 minutes.
Brain Teaser No : 00207
A tank can be filled by pipe A in 30 minutes and by pipe B in 24 minutes. Outlet pipe C can empty the full tank in X minutes.
If the tank is empty initially and if all the three pipes A, B and C are opened simultaneously, the tank will NEVER be full. Give the
maximal possible value of X.
Answer
The maximum possible value of X is 13 minutes 20 seconds.
In one minute,
pipe A can fill 1/30 part of the tank.
pipe B can fill 1/24 part of the tank.
Thus, the net water level increase in one minute is
= 1/30 + 1/24
= 3/40 part of the tank
In order to keep the tank always empty, outlet pipe C should empty at least 3/40 part of the tank in one minute. Thus, pipe C
can empty the full tank in 40/3 i.e. 13 minutes 20 seconds.
Brain Teaser No : 00209
If today is Wednesday, what is one day before the day, after the day, three days after the day before yesterday?
Submitted by : Jennifer Renick
Answer
Thursday
Start backwards.
Today is Wednesday.
The day before yesterday is Monday.
Three days after Monday is Thursday.
The day after Thursday is Friday
The day before Friday is Thursday.
Also, note that the first two conditions cancel each other out as one day before the day, one day after the day is the same day.
Hence, it can be reduced to "three days after the day before yesterday".
Brain Teaser No : 00210
There are 10 cups placed on a table such that 3 are face up and 7 are bottom up. A move is defined as inverting a pair
(compulsorily) of cups.
What is the minimum number of moves required to make all the cups face the same way?
Answer
It is not at all possible. There is no way that one can do that with given Move.
A move is defined as inverting a pair of cups, compulsorily. Also, there are odd number of cups face up (3)and odd number of
cups bottom up (7). Now whenever you make a move you have to invert 2 cups compulsorily. Hence, always odd number of
cups will be face up and bottom up, whatever move you make.
Brain Teaser No : 00211
A man went downstairs to get a drink. He turned of the tap and the lights and went to bed. When he woke up in the middle of the
night he saw thousands of people dead, so he jumped out the window and killed himself.
Why did he kill himself?
Submitted by : Jennifer
Answer
He lived in the light-house. When he turned out the light, he turned out the light-house light that tells ships where the land is! So
some ships must have crashed into the shore and killed people that were there on the ship.
When the man woke up in the middle of the night, he saw thousands of people dead. He realised his mistake and was so sad
and upset that he jumped out the window and killed himself.
Brain Teaser No : 00213
Kate, Demi, Madona, Sharon, Britney and Nicole decided to lunch together in a restaurant. The waiter led them to a round table
with six chairs.
How many different ways can they seat?
Answer
There are 120 different possible seating arrangments.
Note that on a round table ABCDEF and BCDEFA is the same.
The first person can sit on any one of the seats. Now, for the second person there are 5 options, for the third person there are 4
options, for the forth person there are 3 options, for the fifth person there are 2 options and for the last person there is just one
option.
Thus, total different possible seating arrangements are
= 5 * 4 * 3 * 2 * 1
= 120
Brain Teaser No : 00215
Sam and Mala have a conversation.
• Sam says I am certainly not over 40
• Mala says I am 38 and you are atleast 5 years older than me
• Now Sam says you are atleast 39
All the statements by the two are false. How old are they really?
Answer
Sam is 41 and Mala is 37.
Let's invert the teaser and read it like this :
• Sam says I am certainly over 40
• Mala says I am not 38 and you are atmost 4 years older than me
• Now Sam says you are atmost 38
From first statement it is clear that Sam is over 40. Also, from next 2 statements it is clear that Mala is less then 38. Hence the
possibilities are :
Sam = 41, 42, 43, 44, 45, ......
Mala = 37, 36, 35, 34, 33, ......
It also says that the difference between their age is maximum 4 years. Hence, there is only one possible pair i.e. 41 and 37, all
other combination have differences more then 4.
Hence the answer - Sam is 41 and Mala is 37.
Brain Teaser No : 00217
Jim lies a lot. He tells the truth on only one day in a week.
One day he said: "I lie on Mondays and Tuesdays."
The next day he said: "Today is either Sunday, Saturday or Thursday."
The next day he said: "I lie on Fridays and Wednesdays."
On which day of the week does Jim tell the truth?
Answer
Jim tells the truth on Tuesday.
As Jim tells truth only on one day in a week, his statement on day 1 and day 3 both can not be false. Otherwise he tells truth on
more than one days in a week. Also, all three statements are mad on three consecutive days, statement made on day 1 and
day 3 both can not be true. Thus, either the statement made on day 1 or day 3 is true and other is false. Also, the statement
made on day 2 must be false i.e. day 1 is not Saturday, Friday or Wednesday.
Let's assume that the statement 1 is true. Then from the statement 3, day 1 must be either Friday or Wednesday. But it is
already deduced that day 1 is not Saturday, Friday or Wednesday.
Hence, the statement made on day 1 is false and the last statement is true. then from the statement 1, day 3 must be either
Monday or Tuesday. But it is already deduced that day 1 can not be Saturday i.e. day 3 can't be Monday. Hence, Jim tells the
truth on Tuesday.
Brain Teaser No : 00220
An orange colored glass has Orange juice and white colored glass has Apple juice both of equal volumes. 50ml of the orange juice
is taken and poured into the white glass. After that similarly, 50ml from the white glass is poured into the orange glass.
Of the two quantities, the amount of apple juice in the orange glass and the amount of orange juice in the white glass, which one is
greater and by how much?
Answer
The two quantities are equal.
Solve it by taking example. Let's assume that both glasses contain 450 ml of juice each.
Now, 50ml of the orange juice is taken and poured into the White glass. Hence, orange colored glass contains 400 ml of
Orange juice and white glass contains 450 ml of Apple juice and 50 ml of Orange juice i.e. total of 500 ml from white glass
contains 450 ml of Apple juice and 50 ml of Orange juice. It means that every 50 ml from white glass contains 45 ml of
Apple juice and 5 ml of Orange juice.
Similary, 50 ml of juice from white glass is poured into orange glass. Now this 50 ml is not a pure apple juice. It contains 45 ml
of Apple juice and 5 ml of Orange juice.
Hence, Orange glass contains 405 ml of Orange juice and 45 ml of Apple juice. Similary, white glass contains 405 ml of Apple
juice and 45 ml of Orange juice.
Orange Glass White Glass
Orange Juice Apple Juice Orange Juice Apple Juice
Initially 450 ml 0 ml 0 ml 450 ml
50 ml from Orange Glass is poured into White Glass 400 ml 0 ml 50 ml 450 ml
50 ml from White Glass is poured into Orange Glass 405 ml 45 ml 45 ml 405 ml
Now it is clear that the amount of apple juice in the orange glass and the amount of orange juice in the white glass are the
same.
P.S. Here we assumed 450 ml as initial quantity in both the glasses just for simplicity. You can try the same by assuming any
other number. But the answer is the same.
Brain Teaser No : 00216
When Socrates was imprisoned for being a disturbing influence, he was held in high esteem by his guards. All four of them hoped
that something would occur that would facilitate his escape. One evening, the guard who was on duty intentionally left the cell door
open so that Socrates could leave for distant parts.
Socrates did not attempt to escape, as it was his philosophy that if you accept society's rules, you must also accept it's
punishments. However, the open door was considered by the authorities to be a serious matter. It was not clear which guard was
on that evening. The four guards make the following statements in their defense:
Aaron:
A) I did not leave the door open.
B) Clement was the one who did it.
Bob:
A) I was not the one who was on duty that evening.
B) Aaron was on duty.
Clement:
A) Bob was the one on duty that evening.
B) I hoped Socrates would escape.
David:
A) I did not leave the door open.
B) I was not surprised that Socrates did not attempt to escape.
Considering that, in total, three statements are true, and five statements are false, which guard is guilty?
Answer
David is the guilty.
Note that "All four of them hoped that something would occur that would facilitate his escape". It makes Clement's statement B
True and David's statement B False.
Now consider each of them as a guilty, one at a time.
Aaron Bob Clement David
A B A B A B A B
True
Stmts
If Aaron is guilty False False True True False True True False 4
If Bob is guilty True False False False True True True False 4
If Clement is guilty True True True False False True True False 5
If David is guilty True False True False False True False False 3
Since in total, three statements are true and five statements are false. It is clear from the above table that David is the guity.
Brain Teaser No : 00217
Jim lies a lot. He tells the truth on only one day in a week.
One day he said: "I lie on Mondays and Tuesdays."
The next day he said: "Today is either Sunday, Saturday or Thursday."
The next day he said: "I lie on Fridays and Wednesdays."
On which day of the week does Jim tell the truth?
Answer
Jim tells the truth on Tuesday.
As Jim tells truth only on one day in a week, his statement on day 1 and day 3 both can not be false. Otherwise he tells truth on
more than one days in a week. Also, all three statements are mad on three consecutive days, statement made on day 1 and
day 3 both can not be true. Thus, either the statement made on day 1 or day 3 is true and other is false. Also, the statement
made on day 2 must be false i.e. day 1 is not Saturday, Friday or Wednesday.
Let's assume that the statement 1 is true. Then from the statement 3, day 1 must be either Friday or Wednesday. But it is
already deduced that day 1 is not Saturday, Friday or Wednesday.
Hence, the statement made on day 1 is false and the last statement is true. then from the statement 1, day 3 must be either
Monday or Tuesday. But it is already deduced that day 1 can not be Saturday i.e. day 3 can't be Monday. Hence, Jim tells the
truth on Tuesday.
Brain Teaser No : 00221
An electric train is going south but the wind is blowing westward.
Which direction will the smoke from the train be blowing?
Submitted by : Hannah Brooks
Answer
It is an Electric Train. And Electric trains do not produce any smoke. Therefore there is no smoke to be blown.
Brain Teaser No : 00222
Consider a chessboard with a single Rook. A Rook can move any number of square sideways/forward, but not diagonally.
What is the minimum number of moves the Rook needs to make, in order to pass over all the squares on the chessboard and
return to the original position?
Note: Take any square as a starting position for the Rook.
Answer
16 moves
As a Rook can move any number of square sideways/forward, but not diagonally and there are 8 rows and 8 columns on the
chessboard; the Rook needs minimum 16 moves to pass over all the squares and return to the original position.
Brain Teaser No : 00224
Mrs. Kovarik made twenty four Sandwiches. All but seven were eaten.
How many were left?
Submitted by : Kimi
Answer
A Simple one.
It says "all but seven were eaten". Hence, Seven Sandwiches were left.
Brain Teaser No : 00225
Without introducing + signs, arrange six "9" in such a way that they add up to 100.
Submitted by : Calon
Answer
(999-99)/9 = 900/9 = 100
(99 - (-9/9)) * 9/9 = (99 - (-1)) * 1 = 100
99 99/99
Brain Teaser No : 00226
A bus driver was going down a street. He was on the wrong side. He went at a stop sign and didn't signal at a turn. He went under
the minimum speed and yet he didn't get in trouble for his actions.
WHY not?
Submitted by : Kimi
Answer
He was Walking. He is a Bus driver. But it does not say that he was driving.
Brain Teaser No : 00227
Mrs. Watsherface had a garage sale. A custmer named Gina bought an old lamp and a rug. She paid a total of $5.25 for
everything. The rug cost 25 cents more than the lamp.
How much did each cost?
Submitted by : Kimi
Answer
The lamp cost $ 2.50 and the rug cost $ 2.75
A simple one.
Assume that the lamp cost $ L.
Hence the rug must have cost $ (L + 0.25)
Also, total cost is $ 5.25, Hence the equation :
L + L + 0.25 = 5.25
2 * L = 5
L = 2.50
Hence, the lamp cost $ 2.50 and the rug cost $ 2.75
Brain Teaser No : 00228
For many years a BIG company was looking for the universial solvent - a solvent that will dissolve anything.
One day a man walked in a bottle in his hand. The man said "I've come up with the UNIVERSAL solvent!! And if you're lucky, i will
sell it to you for a mere $100,000!"
The president looked seriously at the man and screamed, "Get out of here you stupid creep! You're a dumb liar and a fake!!!"
And with that the president of this huge company picked up the guy and threw him out by his feet.
How did the president know the man was a fake before he even tested the solvent?
Submitted by : Kimi
Answer
The UNIVERSAL solvent is a solvent that will dissolve anything. The man came with Universal solvent in a bottle. Whereas
according to definition of Universal Solvent even bottle should dissolve in it; but it was not. So the President came to know that
he was a FAKE.
Also, if there was a Universal Solvent then it would dissolve anything and everything. Isn't that interesting?
Brain Teaser No : 00230
A sheet of paper has statements numbered from 1 to 100. Statement N says "Exactly N of the statements on this sheet are false."
How many statements are true?
Answer
Only One statement is true - Statement 99
If they are all false, statement 100 would be true i.e. "Exactly 100 of the statements on this sheet are false", which is
contradictory.
If total of 99 statements are false, statement 99 would be true i.e. "Exactly 99 of the statements on this sheet are false". That's
the answer - total 99 statements are false, and statement 99 is true.
Try out for all remaining statements, they all will contradict itself.
Brain Teaser No : 00231
What two numbers comes next in this series?:
1, 2, 3, 6, 7, 14, 15, 30, 31, ? ?
Submitted by : Hannah Brooks
Answer
Next two numbers are 62 and 63.
The pattern is double the number, add one, double the number, add one...
Starting with 1, for next number double the number = 2
For next number add one = 3
Again, double the number = 6
Next add one = 7 and so on ...
Now at 31, for next number double the number = 62
Add one for next number = 63
Brain Teaser No : 00232
There is a one floor house, and everything in it is blue, green or purple. The people are purple, the carpeting is green and the walls
are blue.
What colour do you suppose the stairs are?
Submitted by : Hannah Brooks
Answer
It is a one floor house and one floor house do not have stairs. Hence, there is no question of colour of stairs as there are no
stairs. 0;-)
Brain Teaser No : 00233
A man is looking at a picture, in his mother's, only brother's, nephew's house.
Someone walks by this man and asks "Who are you looking at?". The man answered "I am looking at my daughter's,only brother's,
mother's, father's son-in-law's,son's, father's picture. Also, neither I nor my wife have brothers or sisters."
Whose house is the man in and who is he looking at?
Submitted by : Hannah Brooks
Answer
Man's mothers only brother's nephew is the man himself as man do not have any brothers or sisters. Thus, he is in his house.
Man's daughter's only brother = his son
Son's mother = his wife
Wife's father's son-in-law = man himself (as his wife do not have any brothers or sisters)
Again, man's son's father is himself.
Hence, the man is in his own house and looking at his own picture !!!
Brain Teaser No : 00235
Consider a number 235, where last digit is the sum of first two digits i.e. 2 + 3 = 5.
How many such 3-digit numbers are there?
Answer
There are 45 different 3-digit numbers.
The last digit can not be 0.
If the last digit is 1, the only possible number is 101. (Note that 011 is not a 3-digit number)
If the last digit is 2, the possible numbers are 202 and 112.
If the last digit is 3, the possible numbers are 303, 213 and 123.
If the last digit is 4, the possible numbers are 404, 314, 224 and 134.
If the last digit is 5, the possible numbers are 505, 415, 325, 235 and 145.
Note the pattern here - If the last digit is 1, there is only one number. If the last digit is 2, there are two numbers. If the last digit
is 3, there are three numbers. If the last digit is 4, there are four numbers. If the last digit is 5, there are five numbers. And so
on.....
Thus, total numbers are
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45
Altogether then, there are 45 different 3-digit numbers, where last digit is the sum of first two digits.
Brain Teaser No : 00238
Imagine a triangle of coins on a table so that the first row has one coin in it and the second row has two coins in it and so on. If you
can only move one coin at a time, how many moves does it take to make the triangle point the other way?
For a triangle with two row it is one, for a triangle with three rows it is two, for a triangle with four rows it is three.
For a traingle with five rows is it four?
Submitted by : Alex Crosse
Answer
It takes 5 moves to make the triangle with 5 rows point the other way.
0 = a coin that has not been moved.
X = the old position of the moved coin
8 = the new position of the moved coin.
________X
_______X X
____8 0 0 0 8
_____0 0 0 0
____X 0 0 0 X
_______8 8
________8
For traingle of any number of rows, the optimal number of moves can be achieved by moving the vertically symmetrical coins
i.e. by moving same number of coins from bottom left and right, and remaining coins from the top.
For a triangle with an odd number of rows, the total moves require are :
(N2/4) - (N-4) Where N = 4, 6, 8, 10, ...
For a triangle with even number of rows, the total moves require are :
((N2-1)/4) - (N-4) Where N = 5, 7, 9, 11, ...
Thanks to Alex Crosse for submitting above formulas.
Brain Teaser No : 00239
My brother is a bus driver. Two days ago he drove a bus full of people. At the end of the route the bus was empty but not a single
person had gotton off.
How is this possible?
Submitted by : JD
Answer
Not a single person had gotton off because all of them were either married or widowed or divorced. Not a single of them
was SINGLE i.e no bachelors, all married ;))
Brain Teaser No : 00240
Ben can never tell a lie, George can never tell the truth.
One of them said, "The other one said he was George".
Who said that?
Submitted by : Zachary MOrrison
Answer
The speaker is George.
Since Ben cann't lie, he cann't say that he is George. Similarly, since George cann't tell the truth, he too cann't say that he is
George. Thus, none of them can say that he is George. It means that the speaker is lying. Hence, the speaker must be George.
Brain Teaser No : 00241
He got it in the woods and brought it home in his hand because he couldn't find it. The more he looked for it, the more he felt it.
When he finally found it, he threw it away.
What it is?
Answer
A Thorn
He got a thorn in his hand when he went to the forest. But he couldn't find it, hence he came home with it in his hand. The more
he looked for it, the more pain he felt. Finally, when he found it, obviously he threw it away.
Brain Teaser No : 00242
There is a shortage of tubelights, bulbs and fans in a village - Kharghar. It is found that
• All houses do not have either tubelight or bulb or fan.
• exactly 19% of houses do not have just one of these.
• atleast 67% of houses do not have tubelights.
• atleast 83% of houses do not have bulbs.
• atleast 73% of houses do not have fans.
What percentage of houses do not have tubelight, bulb and fan?
Answer
42% houses do not have tubelight, bulb and fan.
Let's assume that there are 100 houses. Hence, there should be total 300 items i.e. 100 tubelights, 100 bulbs and 100 fans.
From the given data, we know that there is shortage of atleast (67+83+73) 223 items in every 100 houses.
Also, exactly 19 houses do not have just one item. It means that remaining 81 houses should account for the shortage of
remaining (223-19) 204 items. If those remaining 81 houses do not have 2 items each, there would be a shortage of 162 items.
But total of 204 items are short. Hence, atleast (204-162) 42 houses do not have all 3 items - tubelight, bulb and fan.
Thus, 42% houses do not have tubelight, bulb and fan.
Brain Teaser No : 00244
A boy found that he had a 48 inch strip of paper. He could cut an inch off every second.
How long would it take for him to cut 48 pieces? He can not fold the strip and also, can not stack two or more strips and cut them
together.
Submitted by : Kimi
Answer
47 seconds.
To get 48 pieces, the boy have to put only 47 cuts. i.e. he can cut 46 pieces in 46 seconds. After getting 46 pieces, he will have
a 2 inches long piece. He can cut it into two with just a one cut in 1 second. Hence, total of 47 seconds.
Brain Teaser No : 00245
Some will use me, while others will not.
Some have remembered, while others have forgot.
For profit or gain, I'm used expertly.
I can't be picked off the ground or tossed into the sea.
Only gained from patience and time, can you unravel my rhyme?
Answer
Knowledge
The other possible answers are Experience and Wisdom.
Brain Teaser No : 00246
You live in a hilly section of the suburbs and want to buy a new set of table and chairs for the garden. Would you be better off
buying items of furniture that have four legs or three legs? And why?
Answer
A table and chairs with three legs.
Remember you live in a hilly section and also you require furniture for the garden. A table/chair with three legs is more stable,
as three points always lie in a plane.
Brain Teaser No : 00247
This is an unusual paragraph. I'm curious how quickly you can find out what is so unusual about it. It looks so plain you would think
nothing was wrong with it. In fact, nothing is wrong with it! It is unusual though. Study it, and think about it, but you still may not find
anything odd. But if you work at it a bit, you might find out.
Submitted by : Helen Normandin
Answer
There is no letter "E" in the paragraph.
Letter "E" is the most commonly used letter in English language. Hence, its really unusual that there is not a single "E" in that
paragraph.
Brain Teaser No : 00249
Few years ago, a Law teacher came across a student who was willing to learn but was unable to pay the fee. The student struck a
deal saying, "I would pay your fee the day I win my first case in the court". Teacher agreed and proceeded with the law course.
When the course was finished and teacher started pestering the student to pay up the fee, student reminded the deal and pushed
days. Fed up with this, the teacher decided to sue the student in the court of law and both of them decided to argue for themselves.
Did the teacher make the right decision? Will he get his fee from the student?
Answer
This is one of the greatest paradoxes ever recorded in history.
The teacher can put forward his argument saying: "If I win this case, as per the court of law, student has to pay me. And if I lose
the case, student will still pay me because he would have won his first case. So either way i will have to get the money".
Equally student can argued back saying: "If I win the case, as per the court of law, I don't have to pay anything to the teacher.
And if I lose the case, I don't have to pay him because I haven't won my first case yet. So either way, I am not going to pay the
teacher anything".
So once again stuck into Paradox !!!
Brain Teaser No : 00250
There is a 50m long army platoon marching ahead. The last person in the platoon wants to give a letter to the first person leading
the platoon. So while the platoon is marching he runs ahead, reaches the first person and hands over the letter to him and without
stopping he runs and comes back to his original position.
In the mean time the whole platoon has moved ahead by 50m.
The question is how much distance did the last person cover in that time. Assuming that he ran the whole distance with uniform
speed.
Submitted by : manojaba
Answer
The last person covered 120.71 meters.
It is given that the platoon and the last person moved with uniform speed. Also, they both moved for the identical amount of
time. Hence, the ratio of the distance they covered - while person moving forward and backword - are equal.
Let's assume that when the last person reached the first person, the platoon moved X meters forward.
Thus, while moving forward the last person moved (50+X) meters whereas the platoon moved X meters.
Similarly, while moving back the last person moved [50-(50-X)] X meters whereas the platoon moved (50-X) meters.
Now, as the ratios are equal,
(50+X)/X = X/(50-X)
(50+X)*(50-X) = X*X
Solving, X=35.355 meters
Thus, total distance covered by the last person
= (50+X) + X
= 2*X + 50
= 2*(35.355) + 50
= 120.71 meters
Note that at first glance, one might think that the total distance covered by the last person is 100 meters, as he ran the total
lenght of the platoon (50 meters) twice. TRUE, but that's the relative distance covered by the last person i.e. assuming that the
platoon is stationary.
Brain Teaser No : 00251
The word has the first two letters meaning male.
The first three letters meaning female.
The first four letters meaning male.
And the whole word meaning female.
What is the word?
Submitted by : Brittany
Answer
The answer is HEROINE.
The first two letters HE - male.
The first three letters HER - female.
The first four letters HERO - male.
The whole word HEROINE - female.
Brain Teaser No : 00252
A man received a cheque. The rupees has been transposed for paise and vice versa. After spending 5 rupees 42 paise, he
discovered that he now had exactly six times the value of the correct cheque amount.
What amount should he have received?
Answer
He received 6 rupees and 44 paise.
Let's assume that he received a cheque of X rupees and Y paise i.e. (100X + Y)
The amount received by him = 100Y + X
After spending 5 rupees 42 paise, the remaining amount is (100Y + X - 542) which is 6 times the original amount. Thus,
(100Y + X - 542) = 6*(100X + Y)
100Y + X - 542 = 600X + 6Y
94Y = 599X + 542
Using trial-n-error, we get X=6 and Y=44
Hence, he should have received 6 rupees and 44 paise.
Brain Teaser No : 00253
SkyFi city is served by 6 subway lines - A, E, I, O, U and Z.
• When it snows, morning service on line E is delayed.
• When it rains or snows, service on the lines A, U and Z is delayed both morning and afternoon.
• When the temperature drops below 20 C, afternoon service is cancelled on either line A or line O, but not both.
• When the temperature rises above 40 C, afternoon service is cancelled on either line I or line Z, but not both.
• When service on line A is delayed or cancelled, service on line I is also delayed.
• When service on line Z is delayed or cancelled, service on line E is also delayed.
On February 10, it snows all day with the temperature at 18C. On how many lines service will be delayed or cancelled, including
both morning and afternoon?
Answer
The service will be delayed or cancelled on 5 lines - A, E, I, U and Z except line O.
Go through each statement and cross the subway line with delayed or cancelled service.
It is given that it snows all day with the temperature at 18C.
From (1), line E is delayed.
From (2), line A, U and Z are delayed.
From (3), either line A or line O is cancelled.
From (5), line I is delayed because of line A delay.
From (6), line E is delayed because of line Z delay.
As service on line A is delayed, service on line O can not be. Hence, service will be delayed or cancelled on 5 lines - A, E, I, U
and Z except line O.
Brain Teaser No : 00254
One of the four people - Mr. Clinton, his wife Monika, their son Mandy and their daughter Cindy - is a singer and another is a
dancer. Mr. Clinton is older than his wife and Mady is older than his sister.
1. If the singer and the dancer are the same sex, then the dancer is older than the singer.
2. If neither the singer nor the dancer is the parent of the other, then the singer is older than the dancer.
3. If the singer is a man, then the singer and the dancer are the same age.
4. If the singer and the dancer are of opposite sex then the man is older than the woman.
5. If the dancer is a woman, then the dancer is older than the singer.
Whose occupation do you know? And what is his/her occupation?
Answer
Cindy is the Singer. Mr. Clinton or Monika is the Dancer.
From (1) and (3), the singer and the dancer, both can not be a man. From (3) and (4), if the singer is a man, then the dancer
must be a man. Hence, the singer must be a woman.
CASE I : Singer is a woman and Dancer is also a woman
Then, the dancer is Monika and the singer is Cindy.
CASE II : Singer is a woman and Dancer is also a man
Then, the dancer is Mr. Clinton and the singer is Cindy.
In both the cases, we know that Cindy is the Singer. And either Mr. Clinton or Monika is the Dancer.
Brain Teaser No : 00255
Find next two numbers in the series:
60, 30, 20, 15, ?, ?
Answer
12 and 10
The pattern is 60 divide by the position of the number.
The first number is 60/1 = 60
The second number is 60/2 = 30
The third number is 60/3 = 20
The fourth number is 60/4 = 15
The fifth number is 60/5 = 12
The sixth number is 60/6 = 10
Hence the next two numbers in the series are 12 and 10.
Brain Teaser No : 00256
Find the next two numbers in the given series.
0 2 3 4 5 5 7 6 6 7 11 7 13 9 8 8 17 8 19 9 10 13 23 ? ?
Answer
The next two numbers are 9 and 10.
The pattern is - sum of factors in prime factorization of positive integers starting with 1. Note that 1 is not a Prime number.
Integer Prime Factorization Sum
1 - 0
2 2 2
3 3 3
4 2*2 4
5 5 5
6 2*3 5
7 7 7
8 2*2*2 6
9 3*3 6
10 2*5 7
11 11 11
12 2*2*3 7
13 13 13
14 2*7 9
15 3*5 8
16 2*2*2*2 8
17 17 17
18 2*3*3 8
19 19 19
20 2*2*5 9
21 3*7 10
22 2*11 13
23 23 23
24 2*2*2*3 9
25 5*5 10
Hence, the next numbers in the series are 9 10 15 9 11 29 10 31 10 14 19 12 10 37 21 16 11 41 12 43 15 11 25 47 11 14 12
.....
Brain Teaser No : 00257
If A+B=C, D-C=A and E-B=C, then what does D+F stands for? Provide your answer in letter terms as well as in number terms.
Submitted by : David
Answer
J or 10
A simple one.
Assume that each character represents the number equivalent to the position in the alphabet i.e. A = 1, B = 2, C = 3, D = 4 and
so on. Now let's check our assumption.
A + B = C i.e. 1 + 2 = 3
D - C = A i.e. 4 - 3 = 1
E - B = C i.e. 5 - 2 = 3
Thus, our assumption was Correct. Hence, D + F = J i.e. 4 + 6 = 10
Brain Teaser No : 00258
Three convicts are brought into the warden's office. He says he can parole one of them and to decide which one he will parole he
takes out 5 hats (3 red and 2 white). He stands behind them and places a hat on each one of their heads and puts the other two
remaining hats in a drawer.
He tells the prisioners they can look at the others hats and if they can tell which hat they have on they will be the one who is
paroled.
The first man looks at the other two and says, "I don't know."
The second man looks at the others hats and says, "I don't know."
The third man who is blind says, "Even though I have not the gift of sight I can tell by what the others have said that the color of my
hat is..."
What color is the blind mans hat and how does he know?
Submitted by : Anne Hanna
Answer
The color of blind man's hat is Red.
It is sure that the first man saw either both Red hats or one White hat and one Red hat. There are 6 such possibilities:
1) R R R
2) R R W
3) R W R
4) W R R
5) W R W
6) W W R
In all above possibilities, the first man won't be sure of the color of his hat.
Now, the second man knows that the first man saw either both Red hats or one White hat and one Red hat. And, he also knows
that its one of the above 6 possibilities. (like we know ;)) But he says, "I don't know". That means that (2) and (5) are not the
possibilities as in either case he would be sure of the color of his hat (Red) by just looking at the third man's color of hat
(White).
Now, the blind man knows that there are just 4 possibilities - (1), (3), (4), (6) - and in all, the color of his hat is Red.
Brain Teaser No : 00260
If three babies are born every second of the day, then how many babies will be born in the year 2001?
Submitted by : David
Answer
9,46,08,000 babies
The total seconds in year 2001
= 365 days/year * 24 hours/day * 60 minutes/hours * 60 seconds/minute
= 365 * 24 * 60 * 60 seconds
= 3,15,36,000 seconds
Thus, there are 3,15,36,000 seconds in the year 2001. Also, three babies born are every second. Hence, total babies born
= 3 * 3,15,36,000 seconds
= 9,46,08,000
Brain Teaser No : 00261
The letters P, Q, R, S, T, U and V, not necessarily in that order represents seven consecutive integers from 22 to 33.
• U is as much less than Q as R is greater than S.
• V is greater than U.
• Q is the middle term.
• P is 3 greater than S.
Can you find the sequence of letters from the lowest value to the highest value?
Answer
The sequence of letters from the lowest value to the highest value is TUSQRPV.
From (3), Q is the middle term.
___ ___ ___ _Q_ ___ ___ ___
From (4), there must be exactly 2 numbers between P and S which gives two possible positions.
[1] ___ _S_ ___ _Q_ _P_ ___ ___
[2] ___ ___ _S_ _Q_ ___ _P_ ___
From (1), the number of letters between U and Q must be same as the number of letters between S and R. Also, the number of
letters between them can be 1, 2 or 3.
Using trial and error, it can be found that there must be 2 letters between them. Also, it is possible only in option [2] above.
[2] ___ _U_ _S_ _Q_ _R_ _P_ ___
From (2) V must be the highest and the remaining T must be the lowest number.
_T_ _U_ _S_ _Q_ _R_ _P_ _V_
Thus, the sequence of letters from the lowest value to the highest value is TUSQRPV.
Brain Teaser No : 00263
There are 4 novels - Thriller, Mystery, Romance and Science Fiction - writen by Ambrose, Richards, Hooper and Walsh, and
published by Alpha, Beta, Gamma and Theta not in necessarily in the same order.
• The book by Ambrose is published by Theta.
• The Thriller is published by Alpha.
• The Science Fiction novel is by Hooper and is not published by Gamma.
• The Romance novel is by Walsh.
Who are the Author and the Publisher of each novels?
Answer
(Thriller-Richards-Alpha), (Mystery-Ambrose-Theta), (Romance-Walsh-Gamma), (Science Fiction-Hooper-Beta)
From (1), (2) and (3) the Science Fiction novel is by Hooper and published by Beta.
From (4) the Romance novel is by Walsh and published by Gamma.
Now it is obvious that the Mystery is published by Theta and written by Ambrose. And the Thriller is published by Alpha and
written by Richards.
Novel Type Author Publisher
Thriller Richards Alpha
Mystery Ambrose Theta
Romance Walsh Gamma
Science Fiction Hooper Beta
Brain Teaser No : 00264
There is a girl running from some robbers. She holds two solid gold balls each weighing 20 pounds. She comes to an old rope
bridge and a sign that says max weight 130 pounds.
Knowing her weight was 100 pounds, she walked across the bridge with both gold balls, without the bridge breaking. How did she
do that?
Submitted by : Steven
Answer
She juggled the balls so that one ball was always in the air when she walked across the bridge.
Brain Teaser No : 00266
What are the next two letters in the series?
E, O, E, R, E, X, N, T, E, _, _
Submitted by : Katie Cinquegrana
Answer
The next two letters in the series are N and N
The pattern is - Last letter of the numbers starting from 1 when written in English i.e. onE, twO, threE, fouR, fivE, siX, seveN,
eighT, ninE, teN, eleveN, twelvE, etc...
Brain Teaser No : 00267
A stick of length 1 is divided randomly into 3 parts.
What is the probability that a triangle can be made with those three parts?
Answer
The probability, that a triangle can be made by randomly dividing a stick of length 1 into 3 parts, is 25%
A triangle can be made, if and only if, sum of two sides is greater than the third side. Thus,
X1 < X2 + X3
X2 < X3 + X1
X3 < X1 + X2
Also, it is given that X1 + X2 + X3 = 1
From above equations: X1 < 1/2, X2 < 1/2, X3 < 1/2
Thus, a triangle can be formed, if all three sides are less than 1/2 and sum is 1.
Now, let's find the probability that one of X1, X2, X3 is greater than or equal to 1/2.
Note that to divide stick randomly into 3 parts, we need to choose two numbers P and Q, both are between 0 & 1 and P
Now, X1 will be greater than or equal to 1/2, if and only if both the numbers, P & Q, are greater than or equal to 1/2. Thus,
probability of X1 being greater than or equal to 1/2 is = (1/2) * (1/2) = 1/4
Similarly, X3 will be greater than or equal to 1/2, if and only if both the numbers, P & Q, are less than or equal to 1/2. Thus,
probability of X3 being greater than or equal to 1/2 is = (1/2) * (1/2) = 1/4
Also, probability of X2 being greater than or equal to 1/2 is = (1/2) * (1/2) = 1/4
The probability that a triangle can not be made
= (1/4) + (1/4) + (1/4)
= (3/4)
Thus, the probability that a triangle can be made
= 1 - (3/4)
= (1/4)
= 25 %
Thus, the probability that a triangle can be made by randomly dividing a stick of length 1 into 3 parts is 25%
Let's generalise the problem. What is the probability that a polygon with (N+1) sides can be made from (N+1) segments
obtained by randomly dividing a stick of length l into (N+1) parts?
The probability is = 1 - (N+1)*(1/2)^N
The probability tends to 1 as N grows. Thus, it is easier to make a N-sided polygon than it is to make a triangle!!!
Brain Teaser No : 00268
How many ways are there of arranging the sixteen black or white pieces of a standard international chess set on the first two rows
of the board?
Given that each pawn is identical and each rook, knight and bishop is identical to its pair.
Submitted by : Alex Crosse
Answer
6,48,64,800 ways
There are total 16 pieces which can be arranged on 16 places in 16P16 = 16! ways.
(16! = 16 * 15 * 14 * 13 * 12 * ..... * 3 * 2 * 1)
But, there are some duplicate combinations because of identical pieces.
• There are 8 identical pawn, which can be arranged in 8P8 = 8! ways.
• Similarly there are 2 identical rooks, 2 identical knights and 2 identical bishops. Each can be arranged in 2P2 = 2!
ways.
Hence, the require answer is
= (16!) / (8! * 2! * 2! * 2!)
= 6,48,64,800
Brain Teaser No : 00269
My first is in blue, but not in glue
My second in old but not in new
My third in look but not in see
My last in ask but not in plea
My whole has leaves but not a flower
It will help you pass an idle hour
What am I?
Answer
Book
Brain Teaser No : 00270
Can you arrange nine buttons to make ten rows, three buttons in each row?
Submitted by : Nathan Frankl
Answer
Nine buttons can be arranged to make 10 rows of 3 buttons each.
@ @ @
@ @ @
@ @ @
Brain Teaser No : 00272
What are the next two numbers in this series?
1, 4, 1, 5, 9, 2, _, _
Submitted by : Alex Crosse
Answer
Next two numbers are 6 and 5.
The patten is the each digit in the value of PI after the decimal point. The value of mathematical constant PI is 3.1415926536.
Brain Teaser No : 00273
Eleven boys and girls wait to take their seats in the same row in a movie theater. There are exactly 11 seats in the row.
They decided that after the first person sits down, the next person has to sit next to the first. The third sits next to one of the first two
and so on until all eleven are seated. In other words, no person can take a seat that separates him/her from at least one other
person.
How many different ways can this be accomplished? Note that the first person can choose any of the 11 seats.
Answer
There are 1024 different ways.
This is the type of Brain Teaser that can be solved using the method of induction.
If there is just a one person and one seat, that person has only one option.
If there are two persons and two seats, it can be accomplished in 2 different ways.
If there are three persons and three seats, it can be accomplished in 4 different ways. Remember that no person can take a
seat that separates him/her from at least one other person.
Similarly, four persons and four seats produce 8 different ways. And five persons with five seats produce 16 different ways.
It can be seen that with each additional person and seat, the different ways increase by the power of two. For six persons with
six seats, there are 32 different ways.
For any number N, the different possible ways are 2(N-1)
Thus, for 11 persons and 11 seats, total different ways are 210 i.e. 1024
Brain Teaser No : 00275
There are two ropes. Each one can burn in exactly one hour. They are not necessarily of the same length or width as each other.
They also are not of uniform width (may be thiner/wider in middle than on the end), thus burning half of the rope is not necessarily
1/2 hour.
By burning the ropes, how do you measure exactly 45 minutes worth of time?
Answer
If you light both ends of one rope simultaneously, it will burn in exactly a 1/2 hour. Thus, burn one rope from both ends and the
other rope from only one end. Once the one rope (which is burning from both ends) finally burns out (and you know a 1/2 hour
has elapsed), you also know that the other rope (which is burning from only one end) has exactly 1/2 hour left to burn. Since
you only want 45 minutes, light the second end of the rope. This remaining piece will burn in 15 minutes. Thus, totaling 45
minutes
Brain Teaser No : 00277
In Laloo's family, each son has the same number of sisters and brothers. Also, each daughter has twice the number of brothers
than sisters.
How many sons and daughters does Laloo have?
Answer
4 sons and 3 daughters
Laloo must be having one more son then daughter, as each son has same number of sisters and brothers. Using this and little
trial-and-error, we can get the result i.e. 4 sons and 3 daughters.
Each brother has 3 sisters and 3 brothers.
Each sister has 2 sisters and 4 brothers.
Brain Teaser No : 00276
A frog starts climbing 15 feet wall. Each hour he climbs 3 feet and rests for 30 minutes. During rest, he slips back 2 feet.
How many hours does the frog take to reach the top?
Answer
19 hours
A frog climbs 1 foot per 1 1/2 hours as during 30 minutes rest he slips back 2 feet. This way he will climb 12 feet in 18 hours. In
next hour he will climb 3 more feet i.e. he will complete 15 feet in 19 hours and will reach the top of the wall.
Brain Teaser No : 00278
What are the next two in the series?
st, nd, rd, th, th, ..., ...
Submitted by : Christopher Colon
Answer
The answer is th and th
The pattern is the suffix of each number when counted i.e. 1st, 2nd, 3rd, 4th, 5th, 6th, 7th and so on...
Brain Teaser No : 00279
To move a Safe, two cylindrical steel bars 7 inches in diameter are used as rollers.
How far will the safe have moved forward when the rollers have made one revolution?
Submitted by : Calon
Answer
The safe must have moved 22 inches forward.
If the rollers make one revolution, the safe will move the distance equal to the circumference of the roller. Hence, the distance
covered by the safe is
= PI * Diameter (or 2 * PI * Radius)
= PI * 7
= 3.14159265 * 7
= 21.99115
= 22 inches approx.
Brain Teaser No : 00281
On Sunday, December 22, four ships - W, X, Y, Z - started their series of winter cruises to various ports.
• Ship W left at 4:00 PM on Sunday, December 22, for a series of 8-days cruises to Mandva.
• Ship X left at 4:30 PM on Sunday, December 22, for a series of alternating 11-days and 13-days cruises to Alibaug.
• Ship Y left at 5:00 PM on Sunday, December 22, for a series of 5-days cruises to Khihim.
• Ship Z left on Monday for a series of 7-days cruises.
Each ship is scheduled to return back early in the morning after the last day of the cruise and leave again late in the afternoon of
the same day.
On how many days occasions between December 22 and February 28 will three ships be moored at the port?
Answer
On no occasions (other than start date December 22) between December 22 and February 28, three ships will be
moored at the port.
Find out the days on when each ship will be in port:
• Ship W will be in port on days 1, 9, 17, 25, 33, 41, 49, 57 and 65.
• Ship X will be in port on days 1, 12, 25, 36, 49, 60 and 73.
• Ship Y will be in port on days 1, 6, 11, 16, 21, 26, 31, 36, 41, 46, 51, 56, 61 and 66.
• Ship Z will be in port on days 1, 2, 9, 16, 23, 30, 37, 44, 51, 58 and 65.
From above data, it is clear that - on no occasion (other than December 22) will three ships be moored at the port.
Also, on 8 occasions, there will be 2 ships moored at the port.
Brain Teaser No : 00282
I can be long, or I can be short.
I can be grown, or I can be bought.
I can be painted, or I can be left bare.
I can be round, or I can be square.
What am I?
Submitted by : Cain
Answer
Fingernail
Wood is also the possible answer.
Brain Teaser No : 00283
There is a blind man, a deaf man, and a man with no arms.
Something falls from the sky, the blind man sees it, the deaf man hears it and the man with no arms picks it up and puts it in his
pocket.
What is it?
Submitted by : Joe Leonard
Answer
Nothing
"Nothing" falls from the sky, the blind man sees "Nothing", the deaf man hears "Nothing" and the man with no arms picks
"Nothing" up and puts "Nothing" in his pocket.
Brain Teaser No : 00284
While sitting in a club where all single men tell the truth and all married men lie, a woman is approached by three men.
She asks the first guy if he is married, but the music is so loud that she can not hear his answer.
So she turns to the second guy, who tells her, "The first guy said, 'I am married', but he is really single."
Then she turns to the third guy, who says, "The second guy is single."
Can you determine the marital status of each of the three men?
Submitted by : Marie
Answer
All three are married.
A single man would always say that he is single. And a married man would also always say that he is single. It means that no
man in the club would say that he is married. Thus, the second man is lying, so the second man is married.
Since the second man (always lies) says the first man is single, the first man is married.
Similarly, the third man incorrectly says that the second man is single. Hence, the third man is lying and he is married.
Thus, all three are lying and hence, married.
Brain Teaser No : 00286
There are 4 army men. They have been captured by a rebel group and have been held at
ransom. An army intelligent officer orders them to be burried deep in dirt up to their necks. The
format of their burrial are as shown in the figure.
Conditions
• They each have hats on their heads. either black(b) or white (w) look at diagram above. There are total 2 white hats and 2
black hats.
• They only look in front of them not behind. They are not allowed to communicate by talking.
• Between army man 1 and 2, there is a wall.
• Captive man 4 can see the colour of hats on 2 and 3
• 3 can only see 2's hat
• 2 can only see a wall and 1 can see a wall too, but is on the other side
The officer speaks up, "If one of you can correctly tell me the colour of your hat, you will all go scott free back to your contries. If
you are wrong, you will all be killed.
How can one of them be certain about the hat they are wearing and not risk the lives of their fellow souldiers by taking a 50/50
guess!
Submitted by : KWEKU
Answer
Either soldier 3 or soldier 4 can save the life as soldier 1 and soldier 2 can not see colour of any hat, even not their own.. In our
case soldier 3 will tell the colour of his hat.
Soldier 4 can see the hat on soldier 2 and soldier 3. If both are white, then he can be sure about colour of his hat which will be
black and vice-versa. But if one of them is white and one is black, then soldier 4 can not say anything as he can have either of
them. So he will keep mum.
If soldier 4 won't say anyhing for a while, then soldier 3 will know that soldier 4 is not in position to tell the colour of hat on his
hat. It means that colour of soldier 3's hat is opposite of colour of soldier 2's hat. So soldier 3 can tell correctly the colour of hat
on his head which is Black.
Here, we are assuming that all the soldiers are intelligent enough. Also, this solution will work for any combination of 2 Black
hats and 2 White hats.
Brain Teaser No : 00285
Five executives of a Cultural Committee hold a conference in Mumbai.
Mr. A converses in English and Marathi.
Mr. B converses in Hindi and English.
Mr. C converses in Marathi and Hindi.
Mr. D converses in Hindi and Gujarati.
Mr. E, a native Marathi, can also converse in Gujarati.
If a sixth executive is brought in, to be understood by the maximum number of the original five, he should be fluent in which 2
languages?
Answer
The sixth person should be fluent in Hindi & Marathi.
Find out how many executives can understand each of the language.
Three executives speak Hindi - Mr. B, Mr. C and Mr. D. The other two executives - Mr. A and Mr. E, speak Marathi. Thus, the
sixth executive should be fluent in Hindi and Marathi so that original five executives can converse with him.
Brain Teaser No : 00287
In the village called TALAJA, only three TV channels are available - Moon Plus, Mony and Mee TV.
Out of 4000 TV viewers in the village, 1500 watch Moon TV, 2000 watch Mony and 2500 watch Mee TV.
Amongst these, 500 viewers watch Moon Plus and Mony, 800 watch Moon Plus and Mee TV, and 1000 watch Mony and Mee TV.
How many viewers watch all three channels?
Answer
300 viewers watch all three channels.
Let's assume that total X viewers watch all three channels.
total viewers who watch only Moon Plus and Mony = 500-X
total viewers who watch only Moon Plus and Mee TV = 800-X
total viewers who watch only Mony and Mee TV = 1000-X
total viewers who watch only Moon Plus
= 1500 - (500-X) - (800-X) - X
= 200 + X
total viewers who watch only Mony
= 2000 - (500-X) - (1000-X) - X
= 500 + X
total viewers who watch only Mee TV
= 2500 - (1000-X) - (800-X) - X
= 700 + X
We know that total viewers are 4000. Summing up all 7 values,
X + (500 - X) + (800 - X) + (1000 - X) + (200 + X) + (500 + X) + (700 + X) = 4000
X + 3700 = 4000
X = 300
Hence, total 300 viewers watch all three channels.
Brain Teaser No : 00288
Five friends with surname Batliwala, Pocketwala, Talawala, Chunawala and Natakwala have their first name and middle name as
follow.
1. Four of them have a first and middle name of Paresh.
2. Three of them have a first and middle name of Kamlesh.
3. Two of them have a first and middle name of Naresh.
4. One of them have a first and middle name of Elesh.
5. Pocketwala and Talawala, either both are named Kamlesh or neither is named Kamlesh.
6. Either Batliwala and Pocketwala both are named Naresh or Talawala and Chunawala both are named Naresh.
7. Chunawala and Natakwala are not both named Paresh.
Who is named Elesh?
Answer
Pocketwala is named Elesh.
From (1) and (7), it is clear that Batliwala, Pocketwala and Talawala are named Paresh.
From (6) and (5), if Pocketwala or Talawala both are named Kamlesh, then either of them will have three names i.e. Paresh,
Kamlesh and Naresh. Hence, Pocketwala and Talawala both are not named Kamlesh. It means that Batliwala, Chunawala and
Natakwala are named Kamlesh.
Now it is clear that Talawala and Chunawala are named Naresh. Also, Pocketwala is named Elesh.
Brain Teaser No : 00289
You have 13 balls which all look identical. All the balls are the same weight except for one. Using only a balance scale, can find the
odd one out with only 3 weighings?
Is it possible to always tell if the odd one out is heavier or lighter than the other balls?
Submitted by : Brett Hurrell
Answer
It is always possible to find odd ball in 3 weighings and in most of the cases it is possible to tell whether the odd ball is heavier
or lighter. Only in one case, it is not possible to tell the odd ball is whether heavier or lighter.
1. Take 8 balls and weigh 4 against 4.
o If both are not equal, goto step 2
o If both are equal, goto step 3
2. One of these 8 balls is the odd one. Name the balls on heavier side of the scale as H1, H2, H3 and H4. Similarly,
name the balls on the lighter side of the scale as L1, L2, L3 and L4. Either one of H's is heavier or one of L's is lighter.
Weigh (H1, H2, L1) against (H3, H4, X) where X is one ball from the remaining 5 balls in intial weighing.
o If both are equal, one of L2, L3, L4 is lighter. Weigh L2 against L3.
If both are equal, L4 is the odd ball and is lighter.
If L2 is light, L2 is the odd ball and is lighter.
If L3 is light, L3 is the odd ball and is lighter.
o If (H1, H2, L1) is heavier side on the scale, either H1 or H2 is heavier. Weight H1 against H2
If both are equal, there is some error.
If H1 is heavy, H1 is the odd ball and is heavier.
If H2 is heavy, H2 is the odd ball and is heavier.
o If (H3, H4, X) is heavier side on the scale, either H3 or H4 is heavier or L1 is lighter. Weight H3 against H4
If both are equal, L1 is the odd ball and is lighter.
If H3 is heavy, H3 is the odd ball and is heavier.
If H4 is heavy, H4 is the odd ball and is heavier.
3. One of the remaining 5 balls is the odd one. Name the balls as C1, C2, C3, C4, C5. Weight (C1, C2, C3) against (X1,
X2, X3) where X1, X2, X3 are any three balls from the first weighing of 8 balls.
o If both are equal, one of remaining 2 balls is the odd i.e. either C4 or C5. Weigh C4 with X1
If both are equal, C5 is the odd ball. But you can not tell whether it is heavier or lighter.
If C4 is heavy, C4 is the odd ball and is heavier.
If C4 is light, C4 is the odd ball and is lighter.
o If (C1, C2, C3) is heavier side, one of C1, C2, C3 is the odd ball and is heavier. Weigh C1 and C2.
If both are equal, C3 is the odd ball and is heavier.
If C1 is heavy, C1 is the odd ball and is heavier.
If C2 is heavy, C2 is the odd ball and is heavier.
o If (C1, C2, C3) is lighter side, one of C1, C2, C3 is the odd ball and is lighter. Weigh C1 and C2.
If both are equal, C3 is the odd ball and is heavier.
If C1 is light, C1 is the odd ball and is lighter.
If C2 is light, C2 is the odd ball and is lighter.
Brain Teaser No : 00293
A positive integer that, when added to 1000 gives a sum which is greater than when multiplied by 1000.
Find the positive integer.
Answer
The positive integer is 1.
Sum of 1 and 1000 = 1 + 1000 = 1001
Multiplication of 1 and 1000 = 1 * 1000 = 1000
Thus, sum of 1 and 1000 is greater than the multiplication of 1 and 1000.
Brain Teaser No : 00294
A champion weight lifter has a brother that's a doctor, but the same doctor doesn't have a brother. How are they related then?
Submitted by : Brynn
Answer
The champion weight lifter is a sister of the doctor i.e. they are Brother and Sister
The champion weight lifter is a Woman. Her brother is a doctor. The doctor doesn't have a brother, but a sister.
Brain Teaser No : 00300
A boy goes into a shop to buy some sweets. He uses a £1 coin and buys 40p worth of sweets. The shop assistant gives him two
coins for his change.
One of them was not a 50p so how could the boy have gotten his exact change?
Submitted by : Lynsey
Answer
One of them was 10p and the other one was 50p.
The boy got two coins, 50p and 10p. One of them was not a 50p. But the other one was.
Brain Teaser No : 00301
Always talked of,
Never heard,
Never forgotten,
Everybody waits for it,
It always comes,
Never stays,
Always looked for,
Never found.
What am I?
Answer
Tomorrow or Future
Brain Teaser No : 00302
There are 20 people in your applicant pool, including 5 pairs of identical twins.
If you hire 5 people randomly, what are the chances you will hire at least 1 pair of identical twins? (Needless to say, this could
cause trouble ;))
Submitted by : Tim Sanders
Answer
The probability to hire 5 people with at least 1 pair of identical twins is 25.28%
5 people from the 20 people can be hired in 20C5 = 15504 ways.
Now, divide 20 people into two groups of 10 people each :
G1 - with all twins
G2 - with all people other than twins
Let's find out all possible ways to hire 5 people without a single pair of indentical twins.
People from
G1
People from
G2
No of ways to hire G1 without a single pair of
indentical twins
No of ways to hire
G2
Total
ways
0 5 10C0 10C5 252
1 4 10C1 10C4 2100
2 3 10C2 * 8/9 10C3 4800
3 2 10C3 * 8/9 * 6/8 10C2 3600
4 1 10C4 * 8/9 * 6/8 * 4/7 10C1 800
5 0 10C5 * 8/9 * 6/8 * 4/7 * 2/6 10C0 32
Total 11584
Thus, total possible ways to hire 5 people without a single pair of indentical twins = 11584 ways
So, total possible ways to hire 5 people with at least a single pair of indentical twins = 15504 - 11584 = 3920 ways
Hence, the probability to hire 5 people with at least a single pair of indentical twins
= 3920/15504
= 245/969
= 0.2528
= 25.28%
Brain Teaser No : 00303
Computer - Lampshade
Book - Money
Gecko - Wallet
Cookie - ?
What can Cookie go with?
Available Options: Desk, Mouse, Glove, Printer, Tortilla, Checkerboard, Wall, China
Submitted by : Alessandro Tabora
Answer
Cookie can go with either Printer or Checkerboard.
There are two possible answers here.
Answer I - Printer
The patteren is - In each word pair, the first word has N characters whereas the second word has N+1 characters.
Computer (8) - Lampshade (9)
Book (4) - Money (5)
Gecko (5) - Wallet (6)
Cookie (6) - Printer (7)
Answer II - Checkerboard
The patteren is - In each word pair, both words has same number of vowels.
Computer (3) - Lampshade (3)
Book (2) - Money (2)
Gecko (2) - Wallet (2)
Cookie (4) - Checkerboard (4)
Brain Teaser No : 00304
Only one color, but not one size
Stuck at the bottom, but easily flies
Present in the sun, but not in the rain
Doing no harm, and feeling no pain
What am I?
Submitted by : Karen
Answer
Shadow
Shadow is always Black and of different sizes. It is always stuck at the bottom i.e. ground, but easily flies. Always present in the
sun, but not in the rain. And it is doing no harm, and feeling no pain.
Brain Teaser No : 00306
If a bear eats 65 pounds in fish every day EXCEPT every 6th day which it only eats 45 pounds of fish.
If the bear continues this, how many pounds of fish will it eat in 200 days?
Submitted by : David
Answer
The bear will eat 12,340 pounds of fish in 200 days.
It is given that on every 6th day beareats 45 pounds of fish i.e. on day number 6, 12, 18, 24, .... 192, 198 the bear eats 45
pounds of fish.
Total number of 6th days = 200/6 = 33 (the bear eats 45 pounds)
Hence, the normal days are = 200 - 33 = 167 (the bear eats 65 pounds)
Thus, in 200 days, the bear will eat
= (167) * (65) + (33) * (45)
= 10855 + 1485
= 12,340 pounds
Brain Teaser No : 00307
In a small town, there are three temples in a row and a well in front of each temple. A pilgrim came to the town with certain number
of flowers.
Before entering the first temple, he washed all the flowers he had with the water of well. To his surprise, flowers doubled. He
offered few flowers to the God in the first temple and moved to the second temple. Here also, before entering the temple he
washed the remaining flowers with the water of well. And again his flowers doubled. He offered few flowers to the God in second
temple and moved to the third temple. Here also, his flowers doubled after washing them with water. He offered few flowers to the
God in third temple.
There were no flowers left when pilgrim came out of third temple and he offered same number of flowers to the God in all three
temples.
What is the minimum number of flowers the pilgrim had initially? How many flower did he offer to each God?
Answer
The pilgrim had 7 flowers, initially and he offered 8 flowers to each God.
Assume that the pilgrim had X flowers initially and he offered Y flowers to each God.
From the above figure, there are (8X - 7Y) flowers when the pilgrim came out of the third temple. But it is given that there were
no flowers left when he came out of third temple. It means that
(8X - 7Y) = 0
8X = 7Y
The minimum values of X and Y are 7 and 8 respectively to satisfy above equation. Hence, the pilgrim had 7 flowers and he
offered 8 flowers to each God.
In general, the pilgrim had 7N flowers initially and he offered 8N flowers to each God, where N = 1, 2, 3, 4, .....
Brain Teaser No : 00308
The man who makes it sells it.
The man who buys it doesn't use it.
The man who uses it doesn't see it.
What is it?
Submitted by : Lynsey
Answer
A coffin
The man who makes it sells it as it is of no use for him. The man who buys it doesn't use it because he is still alive. And the
man who uses it doesn't see it because he is dead.
Brain Teaser No : 00309
How many parts can a circle be divided into drawing four straight lines? Give the maximum possible answer.
Submitted by : Kimi
Answer
The circle can be divided into 11 parts by drawing 4 straight line.
The trick is whenever you draw a line, it should cut all previously drawn lines and no more than 2 lines should pass through any
intersaction point.
Using above, whenever you draw line number N, the maximum possible parts are increased by N. Intially, without any lines
there is one part. Hence whenver you draw N lines, the maximum possible parts are :
= 1 + (1 + 2 + 3 + 4 + 5 + ...... + N)
= 1 + (N * (N + 1)) /2
Brain Teaser No : 00310
Using 1, 5, 6, 7 only once make 21 using the operations +, -, *, /, ( and ) only.
Submitted by : Timmy Chan
Answer
The answer is
6 / (1 - 5/7) = 21
Thanks to Timmy !!!
Brain Teaser No : 00313
A group of friends went on a holiday to a hill station. It rained for 13 days. But when it rained in the morning, the afternoon was
lovely. And when it rained in the afternoon, the day was preceded by clear morning.
Altogether there were 11 very nice mornings and 12 very nice afternoons. How many days did their holiday last?
Answer
The holiday last for 18 days.
Let's assume the number of days as follows:
Rain in the morning and lovely afternoon = X days
Clear morning and rain in the afternoon = Y days
No rain in the morning and in the afternoon = Z days
Number of days with rain = X + Y = 13 days
Number of days with clear mornings = Y + Z = 11 days
Number of days with clear afternoons = X + Z = 12 days
Solving above 3 equations, we get X = 7, Y = 6 and Z = 5
Hence, total number of days on holiday = 18 days
Brain Teaser No : 00314
You throw away the outside.
You cook the inside.
You eat the outside.
You throw away the inside.
What is it?
Submitted by : Kimi
Answer
Corn.
You throw away the outside - peel the husk
You cook the inside - the ear, the yellow part
You then eat the outside - the cooked yellow part
You throw away the inside - the cob
Brain Teaser No : 00315
A farmer built a fence around his 25 cows in a square region. He built it in such a way that one can see 5 poles from either of the
four sides.
What are the minimum number of poles the farmer must have used?
Answer
16 poles
X X X X X
X X
X X
X X
X X X X X
One pole at each corner and three poles along each side so that one can always see 5 poles from either of the four sides. The
corner pole is shared by two sides and hence reducing the number of poles to 16.
Brain Teaser No : 00317
What appears once in a minute, twice in a moment, but not in a thousand years?
Submitted by : Amanda
Answer
The letter "M"
There is 1 M in a Minute, 2 M's in a MoMent and there are no M's in thousand years.
Brain Teaser No : 00318
What goes up and never goes down?
Submitted by : SleepCaster
Answer
The answer is Age.
As you grow up, you get older and your age goes up. Age never goes down.
Brain Teaser No : 00321
What is harder to catch the faster you run?
Submitted by : Lisa
Answer
Your breath or Shadow
The faster you run, the harder it is to catch your breath/shadow.
Brain Teaser No : 00322
S L I D E
- D E A N
---------
3 6 5 1
Each of seven digits from 0-9 are represented by a different letter above such that the subtraction is true.
What word represents 3651?
Answer
3651 represents LENS.
Let's assign possible values to each letter and then use trial-n-error.
S must be 1.
Then D (under L) must be greater than 5. If D is 6, then L is 0. But then A must be 0 or 1 which is impossible. Hence, the
possible values of D are 7, 8 or 9.
N must be E + 1. Also, D must be A + 5 as the possible values of D are 7, 8 or 9, D can not be (10+A) + 5.
Now using trial-n-error, we get S=1, I=2, L=3, A=4, N=5, E=6 and D=9
S L I D E 1 3 2 9 6
- D E A N - 9 6 4 5
-------------- --------------
3 6 5 1 L E N S
Hence, 3651 represents LENS.
Brain Teaser No : 00323
Find next two numbers in the series :
100, 365, 24, 60, ?, ?
Answer
The next two numbers are 60 and 1000.
The pattern is breaking down the time from Century to miliseconds.
There are 100 years in a century.
There are 365 days in a year.
There are 24 hours in a day.
There are 60 minutes in an hour.
There are 60 seconds in a minute.
There are 1000 miliseconds in a second.
Hence, the sequence is : 100, 365, 24, 60, 60, 1000
Brain Teaser No : 00324
You have just built a house. However, you may only take certain items into the house. You can take doors, but you aren't allowed
any windows. You can't have, but you are allowed coffee. A book is okay, but no paper. Finally, you can take a puppy or kitten, but
you can't take a dog or cat.
Give one more thing that you can/can't take, and explain why.
Submitted by : J W
Answer
Anything with double letters in spelling is allowed and without double letters is not allowed.
If you you look at the spelling of the names of the items that are allowed in the house, you will notice that they all have double
letters i.e. DOOR, BOOK, PUPPY, KITTEN
So you can take items like Coffee, Balloon, Pillow.
Brain Teaser No : 00325
What walk on 4 legs in the morning, 2 legs in the afternoon and 3 legs at the night?
Submitted by : jon
Answer
A human being
A human being crawls on 4 legs (2 legs + 2 hands) when child, walks on 2 legs when young and walks on 3 legs (2 legs +
walking stick) when old.
Brain Teaser No : 00326
The sum of their (father, mother and son) ages is 70. The father is 6 times as old as the son.
When the sum of their ages is twice 70, the father will be twice as old as the son.
How old is the mother?
Submitted by : Tim Sanders
Answer
The mother is 29 years and 2 months old.
Let's assume that son is X years old. Hence, father is 6X years old and mother is (70-7X) years old.
It is given that the sum of their ages is 70, which will total 140 after 70/3 years.
After 70/3 years, son will be (X + 70/3) years old and father will be (6X + 70/3) years old. Also, it is given that after 70/3 years,
the father will be twice as old as the son. Thus,
(6X + 70/3) = 2 * (X + 70/3)
6X + 70/3 = 2X + 140/3
4X = 70/3
X = 35/6
Hence, their ages are
Son = X = 35/6 = 5 years and 10 months
Father = 6X = 6(35/6) = 35 years
Mother = (70 - 7X) = 70 - 7(35/6) = 29 years and 2 months
Brain Teaser No : 00328
How many squares are there in a 5 inch by 5 inch square grid? Note that the grid is made up of one inch by one inch squares.
Submitted by : Kristin Monroe
Answer
There are 55 squares in a 5 by 5 grid.
There are 25 squares of one grid.
There are 16 squares of four grids i.e. 2 by 2
There are 9 squares of nine grids i.e. 3 by 3
There are 4 squares of sixteen grids i.e. 4 by 4
There is 1 square of twenty-five girds i.e. 5 by 5
Hence, there are total 25 + 16 + 9 + 4 + 1 = 55 squares.
You must have noticed one thing that total number squares possible of each size is always a perfact square i.e. 25, 16, 9, 4, 1
For a grid of N by N, the possible number of squares are
= N2 + (N - 1)2 + (N - 2)2 + (N - 3)2 + ......... + 32 + 22 + 12
For 1 by 1 grid, total squares = 12 = 1
For 2 by 2 grid, total squares = 22 + 12 = 5
For 3 by 3 grid, total squares = 32 + 22 + 12 = 14
For 4 by 4 grid, total squares = 42 + 32 + 22 + 12 = 30
For 5 by 5 grid, total squares = 52 + 42 + 32 + 22 + 12 = 55
Brain Teaser No : 00329
Three Gold (G) coins, three Silver (S) coins and three Copper (C) coins are arranged in a single row as follow:
G S C G S C G S C
• Only 2 adjacent unlike coins can be moved at any one time.
• The moved coins must be in contact with at least one other coin in line. i.e. no pair of coins is to be moved and placed
away from the remaining ones.
• No coin pairs can be reversed i.e. a S-C combination must remain in that order in its new positionwhen it is moved.
What is the minimum number of moves required to get all the coins in following order?
C C C S S S G G G
Show all moves.
Answer
Minimum number of moves are 8.
Move Order of Coins
0 G S C G S C G S C
1 G S G S C G S C C
2 G S C G S C C S G
3 G S C G S C C S G
4 G S C C S G S C G
5 G S C C S C S G G
6 G S C C C S S G G
7 C C C S S G G S G
8 C C C S S S G G G
Brain Teaser No : 00331
Draw 9 dots on a page, in the shape of three rows of three dots to form a square. Now place your pen on the page, draw 4 straight
lines and try and cover all the dots.
You're not allowed to lift your pen.
Note: Don't be confined by the dimensions of the square.
Submitted by : Joe Lambe
Answer
Let's number the dots to simplify the explaination.
1 2 3 Y
4 5 6
7 8 9
X
Where X, Y are just two imaginary points.
1. Draw the first line starting from point 1 and passing straight down through points 4, 7 and X.
2. Draw the second line starting from X and passing through 8, 6 and Y.
3. Draw the third line starting from Y and passing through 3, 2 and 1.
4. And now draw the forth and the final line starting from 1 and passing through 5 and 9.
Brain Teaser No : 00333
You've often cut me through in the years
Yet it is you that bursts into tears
Who am I?
Submitted by : Dan Sattary-Javid
Answer
An Onion
Brain Teaser No : 00334
A man has Ten Horses and nine stables as shown here.
[] [] [] [] [] [] [] [] []
The man wants to fit Ten Horses into nine stables. How can he fit Ten horses into nine stables?
Submitted by : Steve Wagner
Answer
The answer is simple. It says the man wants to fit "Ten Horses" into nine stables. There are nine letters in the phrase "Ten
Horses". So you can put one letter each in all nine stables.
[T] [E] [N] [H] [O] [R] [S] [E] [S]
Brain Teaser No : 00335
Two women, X and Y, were selling Oranges in the market. X were selling 3 oranges for a Rupee and Y were selling 2 oranges for a
Rupee.
One day each of them had 30 oranges unsold. They put together the two lots of oranges and decided to sell 5 oranges for Rs. 2.
According to their calculation, 3 oranges for Rs. 1 and 2 oranges for Rs. 1 was exactly the same as 5 oranges for Rs. 2
Now, they were expecting to get Rs. 25 for the oranges, as they would have got, if sold separately. But to their surprise they got
only Rs. 24 for the entire lot of the 60 oranges.
Where did the one rupee go?
Answer
Woman X was selling 3 oranges for a Rupee. Hence, the average price of one orange is (1/3) = Rs. 0.3333
Woman Y was selling 2 oranges for a Rupee. Hence, the average price of one orange is (1/2) = Rs. 0.5
Now they put together 60 oranges. Hence, the average price of one orange is (0.3333+0.5)/2 = Rs. 0.4167
But, they were selling 5 oranges for Rs. 2. Hence, the average price of one orange is 2/5 = Rs. 0.4
The differnce is (0.4167 - 0.4) = 0.0167
There are 60 oranges. Hence (0.0167 * 60) = 1
So here is that one rupee. Thus, one rupee didn't go anywhere, they did their math wrong.
Brain Teaser No : 00338
Insert mathematical functions to convert the 3 numbers on the left side of the equation to equal 6. I filled in the 2's (using the
addition function twice) for you to get you started.
1 1 1 = 6
2 + 2 + 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6
Submitted by : Jon
Answer
(1 + 1 + 1)! = 6
2 + 2 + 2 = 6
(3 * 3) - 3 = 6
sqrt(4) + sqrt(4) + sqrt(4) = 6
5 + (5 / 5) = 6
6 + 6 - 6 = 6
7 - (7 / 7) = 6
8 - sqrt(sqrt(8+8)) = 6
(sqrt(9) * sqrt(9)) - sqrt(9) = 6
Brain Teaser No : 00339
What numbers do X and Y represent in the following series:
2, 6, 12, 20, 30, 42, X, Y
Submitted by : Milind Gadagkar
Answer
X=56 and Y=72
The pattern is the multiplication of two consecutive numbers stating with 1.
First number = 1 * 2 = 2
Second number = 2 * 3 = 6
Third number = 3 * 4 = 12
Forth number = 4 * 5 = 20
Fifth number = 5 * 6 = 30
Sixth number = 6 * 7 = 42
Seventh number = 7 * 8 = 56
Eighth number = 8 * 9 = 72
Alternatively, the patten can be defined as adding a constant after incrementing it by 2 to the previous number.
First number = 2
Second number = 2 + 4 = 6
Third number = 6 + 6 = 12
Forth number = 12 + 8 = 20
Fifth number = 20 + 10 = 30
Sixth number = 30 + 12 = 42
Seventh number = 42 + 14 = 56
Eighth number = 56 + 16 = 72
Brain Teaser No : 00342
What are the next two numbers in the series?
14, 316, 536, 764, ?, ?
Submitted by : Jayn
Answer
The next two numbers are 9100 and 11144.
The pattern is - starting from 1, take 2 consecutive numbers and put the first number with the square of the second numebr.
First number = 1 (2)^2 = 14
Second number = 3 (4)^2 = 316
Third number = 5 (6)^2 = 536
Fourth number = 7 (8)^2 = 764
Fifth number = 9 (10)^2 = 9100
Sixth number = 11 (12)^2 = 11144
Hence, the next two numbers are 9100 and 11144.
Brain Teaser No : 00343
I have two children. At least one of them is a boy. What is the probability that both my children are boys?
My sister also has two children. The older child is a girl. What is the probability that both her children are girls?
Submitted by : Dennis Yancey
Answer
The probability that both my children are boys is 1/3. And that my sister's both children are girls is 1/2.
There are four possibilities of having two children (with the oldest listed first):
1. (Girl, Girl)
2. (Girl, Boy)
3. (Boy, Girl)
4. (Boy, Boy)
As I have at least one boy, there are three possibilities i.e. 2, 3 and 4. And only in one case both are boys. Hence, the reqiured
probability is 1/3.
Similarly, since my sister's older child is girl, there are just two possibilities i.e. 1 and 2. And again, only in one case both are
girls. Hence, the reqiured probability is 1/2.
Brain Teaser No : 00345
What are the next three numbers in the given series?
1 2 3 2 1 2 3 4 2 1 2 3 4 3 2 ? ? ?
Answer
The next three numbers are 3, 4 and 5.
The pattern is - the number of letters in the Roman numeral representation of the numbers i.e. number of letters in I, II, III, IV,
V, VI, VII, VIII, IX, X, XI, XII, XIII, XIV, XV, .....
Hence, the next numbers in the given series are 3(XVI), 4(XVII), 5(XVIII), 3(XIX), 2(XX), 3(XXI), 4(XXII), 5(XXIII), 4(XXIV),
3(XXV), etc...
Brain Teaser No : 00346
A terrorist, after having comitted a crime wanted to cross the border. He knew that a pick up vehicle had been arranged at the
border for him. But the driver would identify him by a code word which the terrorist didn't know. So he mailed to his group leader
using a certain code language. This is what he mailed:
TWDK XJ KWQ GIPQ TIFP X HQQP KI LJQ DK KWQ YIFPQF?
His group leader replied back on mail, saying:
ZIL HQQP KI JDZ KWDK "XR TXJWQJ TQFQ WIFJQJ YQVVDFJ TILCP FXPQ"
Can you decipher the code and make out as to what the terrorist mailed and what was the reply sent back to him?
HINT : In the code language,QUEEN ELIZABETH can be written as ELQQH QCXADYQKW
Submitted by : Milind Gadagkar
Answer
The terrorist mailed : WHAT IS THE CODE WORD I NEED TO USE AT THE BORDER?
The Leader replied : YOU NEED TO SAY THAT "IF WISHES WERE HORSES BEGGARS WOULD RIDE"
Use the hint. It says that "In the code language, QUEEN ELIZABETH can be written as ELQQH QCXADYQKW." It means that
in code language E means Q, L means U, Q means E, H means N and so on.
Q U E E N E L I Z A B E T H
E L Q Q H Q C X A D Y Q K W
Use the above hint and
