※ 引述《Nocp (冲浪..被浪冲 傻傻分不清)》之铭言： : A card hand selected from a standard card deck : consists of 2 kings ,2 queens and a jack. : Three additional cards are selected at random and without replacement : from the remaining cards in the deck . : What is the probability that the enlarged hand contains at least three : kings? : ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ : 由题目知 每抽到一张牌 丢 3张同样回去, 可是不重复所以要扣一张走 = 丢两张回去 : 请问 可以这样分析?! : 1 - P (每次都没抽到 K ) : 3 5 7 : = 1 - ( --- + --- +--- ............) : 5 7 9 : 那接下来该怎办...!? 我的解读是： 从52张牌里(standard card deck)，抽出包含两张K，两张Q跟一张J牌的一手牌； 再采抽出不放回方式从余下的47张牌里抽出三张牌，问总共抽出的8张牌里至少有3张K 的机率? Ans： 令X为抽出的三张牌里K的张数，则 X ~ Hypergeo (n=3，K=2，N=47) 所求即为P (X >= 1 ) = 1 - P ( X = 0 ) 2C0 * 45C3 = 1 - ---------- 47C3 135 = ------- = 0.1249 1081 --

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