Here's a fun little puzzle/question that I first saw on the wonderful series NUMB3RS, but was actually posed to a famous columnist.
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?
I'll provide a link to the full answer, and my even plainer language explanation, in the next couple of days.