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两张牌都是 K 的概率

both of your cards are Kings

专题
Probability / 概率
难度
L4

题目详情

You are dealt exactly two playing cards from a well- shuffled standard 52- card deck. The standard deck contains exactly four Kings. What is the probability that both of your cards are Kings?

解析

用组合计数：

P(两张都是K)=(42)(522)=61326=1221≈0.00452.\mathbb{P}(\text{两张都是K})=\frac{\binom{4}{2}}{\binom{52}{2}}= \frac{6}{1326}=\boxed{\frac{1}{221}}\approx 0.00452.