easy   Probability

Missing Million II

A release-checked easy problem for training Conditional Probability.

Question

You are on a game show with $3$ doors in front of you. One of the doors has $\$1$ million inside, while the other two are empty. In the final round, the host lets you spin a wheel two times that may reveal which door the $\$1$ million is in. On each spin, this wheel will tell you the location of the $\$1$ million $3/5$ of the time, independent between spins. Otherwise, it tells you nothing about the location of the money. After two spins, if the wheel has not revealed to you the location of the $\$1$ million, you must guess uniformly at random. What is the probability you locate the $\$1$ million door?

Practice focus

This Probability problem is tagged Conditional Probability. State the random variables and conditioning information explicitly, then check the result against boundary cases before opening hints or a solution.

Explore related collections

Reviewed questions in this area

easyBaby BoyReviewed

Probability · SIG, DE Shaw

easyBad BagelReviewed

Probability · SIG, Jane Street