Q5Section I (Objective (Q1–Q80))5 of 80
Probability — expected escape time for trapped miner
A miner is trapped in a mine containing 3 doors. The first door leads to a tunnel that will take him to safety after 3 hours of travel. The second door leads to a tunnel that will return him to the mine after 5 hours of travel. The third door leads to a tunnel that will return him to the mine after 7 hours of travel. Assuming that the miner is equally likely to choose any of the doors, what is the expected length of time until he reaches safety?
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