Which cards test a vowel-even rule
Question
Four cards each have a letter on one side and a number on the other. Lying on the table they show a vowel, a consonant, an even number and an odd number. You must check the rule "any card with a vowel on one side has an even number on its reverse". Which cards need to be flipped, and only those?
Short answer
The vowel and the odd number. The vowel might hide an odd number, and the odd number might hide a vowel; either would break the rule. The consonant is unconstrained, and an even number may have anything on its back, so turning them tells you nothing.
Adapted from Joshi, Denson & Downes, Quant Job Interview Questions and Answers, Q8.15, p.277; question and answer rewritten by SelfMadeQuant.com.
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Open the worked solutionLessons behind this question
- Sample Spaces, Events, and the Probability Axioms
- Conditional Probability, Total Probability, and Bayes' Rule
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