Best stopping card for an ace-placement prize
Question
Alice chooses a number from to , then turns over the top cards of a well-shuffled standard deck. She wins if the th card she turns is an ace and exactly one ace remains among the unturned cards. Which maximises her chance of winning?
Short answer
. Winning needs two aces among the first cards, an ace at position , and one ace in the rest, so the probability is proportional to . The continuous maximiser is about ; comparing integers, gives versus at .
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Open the worked solutionLessons behind this question
- Optimisation Problems
- Constrained Optimisation and Lagrange Multipliers
- Sample Spaces, Events, and the Probability Axioms
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