国际顶尖MBA申请交流平台--TOPWAY MBA

标题: Prep-PS-71 [打印本页]

作者: lisalee 时间: 2010-5-31 12:15 标题: Prep-PS-71

A certain law firm consists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner? (Two groups are considered different if at least one group member is different.)
(A) 48
(B) 100
(C) 120
(D) 288
(E) 600

作者: 篮球火 时间: 2010-5-31 13:02

至少有一个senior，一共三种情况，一种就是有一个senior, c41乘以c62=15, 第二种二个senior, c42乘以c61=36, 第三种，三个，c43=4 三种情况相加=100

作者: worker 时间: 2010-5-31 13:05

团队里至少有一位senior组合=团体所有组合－团体里皆是三位junior的組合

10！/[3!(10-3)!]-6![3!(6-3)!]=100

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