Second pair from a 40-card deck missing a pair
Question
A deck has cards: four copies each of the numbers through . One pair of cards with the same number is taken out of the deck. Two cards are then drawn at random from the remaining cards. What is the probability that these two cards also have the same number?
Short answer
. After the pair is removed, cards remain: nine numbers still have four copies and one has two. Matching pairs number out of .
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Open the worked solutionLessons behind this question
- Counting and Combinatorics
- Sample Spaces, Events, and the Probability Axioms
- Conditional Probability, Total Probability, and Bayes' Rule
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