Three prisoners are one behind the other. Each wearing a hat on the head fired at random from 2 white hats and 3 blacks. Thus, the first sees the hats of 2 next, the 2nd, only the following and the 3rd see nobody. That devine the color of his hat is released.One who gives a false response is dead, but the one who do not know will remain prisoner. Request that prime (who sees the 2 other) if he knows the color of his hat. He replied that not. We are asking the 2nd (who cannot see that the next), it also responds not. We are asking the 3rd who does not see person and knows how to answer. How is this possible ?