MathDB

15

Part of 2008 Harvard-MIT Mathematics Tournament

Problems(1)

Game Show

Source:

4/6/2008
In a game show, Bob is faced with 7 7 doors, 2 2 of which hide prizes. After he chooses a door, the host opens three other doors, of which one is hiding a prize. Bob chooses to switch to another door. What is the probability that his new door is hiding a prize?
probability