CareerPrep.

You have 3 glasses and 10 coins. The objective is to distribute ten coins among the three glasses such that each and every glass has an odd number of coins.

Solution

:

Let us try to divide 10 into 3 parts. Following are the possible combinations: -

1 + 1 + 8

1 + 2 + 7

1 + 3 + 6

1 + 4 + 5

2 + 2 + 6

2 + 3 + 5

2 + 4 + 4

3 + 3 + 4

Now from this, we can see that there is no way we can divide 10 into three odd parts, as there will always be one even number. Therefore, we cannot conventionally divide the coins into three odd parts.

However, interviewers ask questions like this to check a candidate’s capacity to think out of the box. This problem for instance although we cannot solve it conventionally, we can do the following: -

Let us distribute the coins in the following way 5 : 3 : 2, now we have odd numbers in the 1st and 2nd glass while the 3rd glass has even number.

Pick up the 3rd glass and place it inside the 2nd glass. In this way, the 2nd and 3rd glasses essentially become one and contain 5 coins which is an odd number.

This same solution also applies if we distribute the coins in a 7 : 2 : 1 ratio.