Puzzle – Blind Games

Given that you are in a dim room where a table is kept. There are 50 coins put on the table, out of which 10 coins show tails and 40 coins show heads. The task is to separate this arrangement of 50 coins into 2 groups (not really a similar size) such that both groups have the same number of coins showing tails, you can perform any number of flips on any coin. 

Blind Games

Solution:

At random, divide the coins into two groups of 10 (Pile1) and 40 (Pile2). The heads will be distributed across the two piles in some way. Consider there are N tails (0 ≤ N ≤ 10) in Pile1. So there are (10-N) tails in Pile2 and (10-N) heads in Pile1.

Division in two groups

Now if you flip all the coins in Pile1 then all heads will become tails and vice versa. So, the number of tails in Pile1 is now (10-N) which is similar to the number of tails in Pile2.

Similar Question : https://www.geeksforgeeks.org/puzzle-24-10-coins-puzzle/