Monday, April 11, 2011

The Coin Flip

Here's a quick riddle. Setup: you are blindfolded, wearing thick gloves. There are twenty coins on the table in front of you: ten are heads and ten are tails. You do not know which; you cannot see them because of the blindfold and you cannot feel them because of the gloves. The only thing you can do is flip coins upside down or move them around.

You are to divide the coins into two equal groups (thus ten coins each). The assignment is to get the same number of heads and the same number of tails in both groups. How can you do it? No peeking!

Hint: The solution is easy. But reasoning to that point... less so!