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, say 1, and the host, who knows what’s behind the doors, opens another door, say 3, which has a goat. He says to you, “Do you want to pick door 2?” Is it to your advantage to switch your choice of doors?1http://www.marilynvossavant.com/articles/gameshow.html
This problem, called the Monty Hall Problem, is one of my favorite mathematical puzzles. Because it has been discussed to death (a quick Google search brings up hundreds of thousands of results), there is probably not much that I can add to the discussion. That being said, it is an interesting problem, and I think that it is worth sharing.