Monte Hall problem: You are contestant on "Let's make a deal." One of three doors has a million-dollar prize behind it, the other two have goats. You choose a door, say door #1. To add drama, the host opens one of the doors you did not pick (say door #2) and behind it is a goat. Should you switch to door #3 or stick with door #1. Why? Assume that the host knows what door the prize is behind and opens one with a goat. If both 2 and 3 have a goat behind them, the host chooses one to open at random.