Bus wait when some gaps include an hour-long refuel
Question
Buses are scheduled minutes apart. Before each gap, independently, the driver stops to refuel with probability , and a refuel adds minutes to that gap (making it minutes). You arrive at the stop at a uniformly random time of day. What is your expected wait, in minutes, for the next bus?
Short answer
minutes (18.125). You are more likely to land in a long gap (inspection paradox). Your expected wait is for gap length : and , giving .
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Open the worked solutionLessons behind this question
- Conditional Expectation and Variance Revisited
- Conditional Probability, Total Probability, and Bayes' Rule
- Worked Examples — Probability Trees, Monty Hall, and Bayesian Updating
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