three-doors. This is the classic three door probability problem. The setup: you are on a game show and the host tells you can open one of three doors, one of which has a car behind it and the other two have a goat. You make a choice, and then the show host decides to make things interesting and opens one of the other doors that does *not* have the car behind it. The host then asks if you would like to switch choices, or keep your original choice. This script proves that you should ALWAYS switch, and that it is a 66% repeating chance that you will get the car if you do.