Mind Teasers :
Famous Probability Interview Problem
James Horner is having two coins in his hand. Out of the two coins, one is a real coin and the second one is a faulty one with Tales on both sides. He blind folds himself choose a random coin and tosses it in the air. The coin falls down with Tale facing upwards.
What is the probability that this is the faulty coin?
Two friends , Torres and Lampard, meet after a long time.
Torres: Hey, how are you man?
Lampard: Not bad, got married and I have three kids now.
Torres: That's awesome. How old are they?
Lampard: The product of their ages is 72 and the sum of their ages is the same as your birth date.
Torres: Cool..But I still don't know.
Lampard: My eldest kid just started taking piano lessons.
Torres: Oh now I get it.
The sum of their ages is the same as your birth date. That could be anything from 1 to 31 but the fact that Torres was unable to find out the ages, it means there are two or more combinations with the same sum. From the choices above, only two of them are possible now.
Birbal is a witty trader who trade of a mystical fruit grown far in north. He travels from one place to another with three sacks which can hold 30 fruits each. None of the sack can hold more than 30 fruits. On his way, he has to pass through thirty check points and at each check point, he has to give one fruit for each sack to the authorities.
How many mystical fruits remain after he goes through all the thirty check points?
Remember we told you that Birbal is a witty trader. So his sole motive is to get rid of the sacks as fast as he can.
For the first sack:
He must be able to fill fruits from one sack to other two sacks. Assume that he is able to do that after M check points. Now to find M,
(Space in first sack) M + (Space in second sack) M = (Remaining fruits in Third Sack) 30 – M
M = 10
Thus after 10 checkpoints, Birbal will be left with only 2 sacks containing 30 fruits each.
Now he must get rid of the second sack.
For that, he must fill the fruits from second sack to the first sack. Assume that he manages to do that after N checkpoints.
(Space in First Sack) N = (Remaining fruits in second sack) 30 – N
N = 15
Thus after he has crossed 25 checkpoints, he will be left be one sack with 30 fruits in it. He has to pass five more checkpoints where he will have to give five fruits and he will be left with twenty five fruits once he has crossed all thirty check points.
I am a book lover and i saw a book for Pound 97.
I am short of money , so i borrowed Pound 50 from my sister and 50 from my brother = Pound 100.
I bought the book, and had Pound 3 change. I gave brother Pound 1 and my sister Pound 1 and kept the other Pound 1 for myself. Now I owe my mum Pound 49 and my brother Pound 49. 49+49 = 98 + my Pound 1 = 99.
I borrowed my parents (Pound 50 + Pound 50 = Pound 100).
I bought the book for Pound 97 and i had Pound 3 change.
So, the money that i borrowed and bought the book are Pound 100 (borrowing money)
and the change Pound 3 also the borrowing money the book is Pound 97
Total: Pound 97 + Pound 3(the change) = Pound 100
The money that i used to buy the book all i borrowed.
Pound 97 is the borrowing money, change: Pound 3 also the borrowing money. Pound 97 + Pound 3 = Pound 100
A petri dish kept in a lab has a colony of healthy bacteria. Every bacterium divides itself into two in exactly two minutes. Now the colony started with a single cell at 2 pm. If the petri dish was exactly half full of bacteria at 3 pm, when will the dish become full of bacteria?
Since every bacterium divides into two in two minutes and we know the fact that the dish was half filled with bacteria at 3 pm, after exactly 2 minutes, all will divide into two and will fill the petri dish. Thus, the petri dish will become full at 3:02 pm.
Before going to work, Inspector Montalbano got into the fight with his wife. After coming back from the work he found out that the police was in the home and his wife had just killed a burglar.
The police told that she killed the burglar in self-defense. She told her husband the story that she heard a doorbell and thought that it was me and as soon as she opened the door, the burglar jumped into her and she was so scared that she killed burglar immediately with the knife. Inspector Montalbano asked the police to arrest her wife for murder conspiracy. Why?
In a contest, four fruits (an apple, a banana, an orange, and a pear) have been placed in four closed boxes (one fruit per box). People may guess which fruit is in which box. 123 people participate in the contest. When the boxes are opened, it turns out that 43 people have guessed none of the fruits correctly, 39 people have guessed one fruit correctly, and 31 people have guessed two fruits correctly.
How many people have guessed three fruits correctly, and how many people have guessed four fruits correctly
It is not possible to guess only three fruits correctly: the fourth fruit is then correct too! So nobody has guessed three fruits correctly and 123-43-39-31 = 10 people have guessed four fruits correctly.
Jasmine, Thibault, and Noah were having a night out and decided to order a pizza for $10. It turned out that Jasmine and Thibault were hungrier than Noah. They both ate 6 slices a piece, and Noah got to eat just 2 slices.
Now they want to do a fair split of money. The problem is that none of them have coins with them. Thus, they want to round off the cost to nearest dollar.
Since Jasmine and Thibault ate equal amount, they should pay the same amount. But since that's not possible, they can decide with 'rock, paper, scissor' or an equivalent measure to determine who will pay the extra dollar. Now, let's assume tha Jasmine pays $1 extra after losing
Jasmine will pay $5, Thibault will pay $4 and Noah will pay $2.
If the pizza's cost was $11, we can simply keep the same offset and divide. Jasmine is paying 6% more, Thibault is paying 15% more and Noah is paying 27% more.
Keeping the offset same both Jasmine and Thibault will pay $5 each and Noah will pay $1.
4 + 9 = 1
The trick to solve is to assume the first number as the time in AM and the second number is the number of hours you have to add to it. You'll find the time in PM when you do that.
There is no reason whatever why the customer's original deposit of Rs.100 should equal the total of the balances left after each withdrawal.
The total of withdrawals in the left-hand colum may equal Rs.100, but is is purely coincidence that the total of the right-hand column is close to Rs.100.
Let us show another example, but starting with Rs.200 in the bank:
Withdrawals Balance left
Moral of this story? Don't Total Balances