What is the 'Monty Hall Problem'?

What is the 'Monty Hall Problem'?

Approach: Describe the probability of winning after switching doors.

A probability puzzle based on a game show. After picking one of three doors, the host opens a losing door. Switching doors increases your winning probability from 1/3 to 2/3.

Follow-up: Why does switching help?

Key concepts: conditional probability, counter-intuitive.