1 Rupee Puzzle Solution

Well the trick is in the puzzle itself and you should read it twice thrice to understand it.

When they pay 10 rupees each to the waiter they had given 30 rupees in total.

When waiter returns 5 rupees to them they have paid 25 rupees to the cashier.

Now the waiter return them 3 rupees so they have paid 25 rupees to the cashier and 2 rupees to the waiter.

so in total 25+ 3 +2 =30 rupees.

and the amount paid in restaurant is 25(cashier) + 2(waiter) = 27 = 3 x 9. So they pay 9 rupees each for the meal and got 1 rupee back.

1 Rupee Puzzle

This is one of the tricky puzzles asked in interviews.

Three friends go for a lunch at a restaurant. The bill for the lunch is 25 rupees. They all pay 10 rupees each and the waiter took the money to the cashier.

The cashier deducted the amount and gave 5 rupees to the waiter. But the waiter was not able to split the money among the three friends so he keeps 2 rupees as a tip and give 1 rupee each to the friends.

Now :

They all paid 10 rupees and got 1 back so actual money paid by them = Rs 9
They were 3 friends so total money paid by them will be = Rs 27
Waiter keeps 2 rupees as a tip so total = 27 + 2 =29

So where did the one rupee go?

Click here for the Solution

Number of Girls Puzzle Solution

Well this is a simple probability puzzle and most of the time people answer this puzzle correctly.

Let the number of couples in the country be X. So there will be X boys in the country as each couple will have one boy.

So probability of a girl child will be = 1* probability of one girl + 2* probability of two girls + 3 * probability of three girls + ...

number of girls = 0 + 1 x (0.5 x 0.5 x X) + 2 x (0.5 x 0.5 x 0.5 x X) + 3 x (0.5 x 0.5 x 0.5 x 0.5 x X) + number of girls = 0 + X/4 + X/4 + 3X/8 + .......

So if you solve this equation will approximation you will get
number of girls = X

So Ratio = 1:1

and the researcher is right as the ratio of girls to boys in the country will be same.

Number of Girls Puzzle

This puzzles is one of the classic probability puzzle asked in most of the interviews.

There is a country A where every family wants a boy. So each family continues having babies till they have a boy in their family.

This issue was raised to the health authority of the country but the head of the health department told that this is good as advised by one of our mathematician researcher in our department.

So how is this condition good and what is the ratio of boys to girls in the country.

Assume that the probability of having a girl or a boy is same.

Click here for the solution

Heaven or Hell Puzzle Solution

You have to think a bit for this puzzle.

the question is
If I asked the other gatekeeper which door leads to heaven, what would he tell me?

The door that the gatekeeper tells will be the one that leads to hell as if it is the gatekeeper who speaks truth he will tell the truth and the other gatekeeper will lie so you will get the door which will lead you to hell.

If it is the gatekeeper who speaks lie he will tell lie by telling you the door which goes to hell.

So ultimately you will get the door which goes to hell if you ask this question to any of the guards.

Heaven or Hell Puzzle

This is one of the classic puzzles asked in interviews nowadays.

You are standing before two doors.One door leads to the heaven and the other leads to Hell but you don't know what hides behind the doors. There are two gatekeepers. You know one of them always tells the truth and the other always lies, but you don't know who is the honest one and who is the liar.

You can only ask one question to one of them in order to find the way to heaven. What is the question?

Click here for the solution