Father's Gift

Once upon a time lived a man who had three sons and… a car. An old car.
He decided to buy a new car for himself and give the old car to one of his sons.
He also decided that the car should go to the son who has the sharpest mind and the quickest reflexes.
So, this is what he did. He showed them two white hats and three black hats. Then he told them to keep their eyes shut, chose three hats, and put them on their heads. He told them to open their eyes and look at each other. The first one who guesses the color of the hat on his head is the one who will get the car.

After few seconds one of the sons said: "Black!"
The father presented him with the car keys .

How did this son guess the color of the hat he was wearing?