A probability problem derived from a 1950s quiz challenge, where participants had to guess which of three doors concealed a prize, but were allowed to change their their initial choice after the quizmaster (Monty Hall) had opened one of the remaining doors. An example of a problem where common sense may not help and careful calculation is needed.

Defined on page 26

Used on pages 25, 26, 27, 28

### Links:

- Wikipedia: Monty Hall problem
- mathworld.wolfram.com: Monty Hall Problem