1/13

来源: jinjing 于 2010-05-28 18:36:11 [] [旧帖] [给我悄悄话] 阅读数 : (38 bytes)

P(E/F)=P(E&F)/P(F)=(1/49)/(13/49)=1/13

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• The answer only for 7 families.n families is (n-1)/(7n-1) -jinjing- ♀ 给 jinjing 发送悄悄话 (24 bytes) () 06/01/2010 postreply 11:13:51

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