You have a square. What you have to do is cut and reassemble the square such that you create a Red Cross sign that has the same volume as that of the square.
There was a blind man. He had four socks in his drawer either black or white. He opened it and took out two socks. Now the probability that it was a pair of white socks is 1/2.
Can you find out the probability that he had taken out a pair of black socks ?