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Probability 9.0/10

The Lost Boarding Pass

100 passengers board a plane with 100 assigned seats. The first passenger lost his ticket and sits in a uniformly random seat. Each subsequent passenger sits in their own seat if it is available, otherwise in a uniformly random empty seat. What is the probability the last passenger sits in their own assigned seat? Express as a fraction.

Related problems & prerequisites

Worth solving first

Source: Classic airline-seating probability puzzle in wide circulation; no traceable original source. Statement written for AxiomIQ.