Monty Hall

The Monty Hall problem is a probability puzzle based on a game show scenario. You choose one of three doors, behind one is a prize, and the other two hide goats. After your initial choice, the host—who knows what's behind the doors—opens one of the remaining doors to reveal a goat. You're then given the option to stick with your original choice or switch to the other unopened door. Statistically, switching doubles your chances of winning from 1/3 to 2/3, because the host’s reveal provides additional information that alters the probabilities.