Here’s how it went: Suppose you're on a game show, and you're given the choice of three doors. Behind one door is a car; behind the others, goats. You pick a door (let's call it door number one) and the host, who knows what's behind them each, opens another door (number two). This one has a goat. He then says to you, "Do you want to pick door number three?" Is it to your advantage to switch your choice from one to three?