15,213 math problems. Every answer checked.

Free, no ads · 17 subjects · 152 topics

Problem of the day

Markov chains and Monty Hall · Probability · Earlier days

Monty Hall: car behind door three

Three closed doors hide a car behind one door and goats behind the other two, with the car placed uniformly at random. The contestant picks door 1 without knowing where the car is. Monty, who knows where the car is, then opens one of the other two doors, always one with a goat behind it, choosing at random if he has a choice. Suppose Monty opens door 2. What is the probability that the car is behind door 3? Round to two decimal places.

Sign in to save your progress.

Start solving