求问大牛PREP2012中一道PS题

helenlily25 · 发表于 2012-11-18 09:04:16

A certain law firm cosists of 4 senior partners and 6 junior partners. How many different groups of 3 partners can be formed in which at least on 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

烦劳各位G友指点啦，呵呵谢啦

afterblack · 发表于 2012-11-18 09:11:20

答案是什么啊，我数学菜鸟，我用A103-A63是600

Jaycandoit · 发表于 2012-11-18 11:16:06

楼上错了，这是组合问题，不是排列问题

10个里面选三个所有的情况是C（10，3）=120
然后减去三个人全是junior partners的情况，6个里选3：C（6，3）=20

所以至少有一个senior partner的情况是120-20=100

求问大牛PREP2012中一道PS题

所属分类: GMAT考试

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