olymmath

USAMO 1975 Problem 5

  • Day 2
  • Answer

A pack of n\mathrm{n} cards, including three aces, is well shuffled. Cards are turned over in turn. Show that the expected number of cards that must be turned over to reach the second ace is (n+1)/2(\mathrm{n}+1) / 2.

Dataset text NuminaMath olympiads. Quoted with source.

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(\mathrm{n}+1) / 2

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