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Airplane Seating Probability

HardStatistics & Probability00:00
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Problem

100 people are boarding an airplane. The first person loses their ticket and picks a seat at random. The next 98 people will sit in their assigned seats if available, or choose a random remaining seat if occupied. What is the probability that the 100th person sits in their assigned seat?

Asked in the Superday Round 3 stage. Probability brainteaser.

Requirements

  1. Derive the probability using conditional probability or symmetry.
  2. State the result as an exact probability and percentage.
  3. Explain why the answer is not simply 1/100.
  4. Verify the result with a simulation.