标题: 求助！数学prep07的一道排列组合的题 [打印本页] 作者: 你最珍贵187 时间: 2018-1-23 23:19 标题: 求助！数学prep07的一道排列组合的题 Of the 12 temporary employees in a certain company, 4 will be hired as permanent employees. If 5 of the 12 temporary employees are women, how many of the possible groups of 4 temporary employees consist of 3 women and 1 man?
答案是70。解析过程：C(5,3)*C(7,1)=70
我想问的是，为什么不考虑C（12，4），也就是先选出来4个人的情况。