甲袋中有可识别的m个白球,n个黑球,乙袋中有可识别的n个白球,m

甲袋中有可识别的m个白球,n个黑球,乙袋中有可识别的n个白球,m个黑球(mn),现从两袋中各摸一个球.事件A:“两球同色”,B:“两球异色”,则P(A)与PB)的大小为(  )

A.PA)<PB

B.PA)=PB

C.PA)>PB

D.视mn大小确定

答案

思路解析:事件A,B是对立事件.其中P(A)=

P(B)=

P(B)-P(A)=>0(mn),

所以P(B)>P(A).

答案:

A

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