0:00
Probability 6.9/10

Monty Hall, Generalized

You are on a game show with 4 doors. One hides a prize, three hide nothing. You pick a door. The host, who knows where the prize is, opens 2 of the remaining 3 doors (always revealing no prize). You may switch to the one remaining unopened door. What is the probability of winning if you switch? Express as a fraction.

Related problems & prerequisites

Worth solving first

Source: Generalisation of the Monty Hall problem, posed by Steve Selvin (1975) and made famous by Marilyn vos Savant (1990). Statement written for AxiomIQ.