[求助]数学题真题 GIGI第一套上面的

aggiesim · 发表于 2009-7-7 21:50:00

A certain university will select 1 of 7 candidates eligible to fill a position in the mathematics department and 2 of 10 candidates eligible to fill 2 identical positions in the computer science department. If none of the candidates is eligible for a position in both departments, how many different sets of 3 candidates are there to fill the 3 positions?

A. 42

B. 70

C. 140

D. 165

E. 315

麻烦各位大侠给点帮助吧~翻译和解答下

alan722 · 发表于 2009-7-7 22:58:00

一所大学从7个候选人中选一个到数学部门，从10个候选人中选2个到科学部门（2个职位没有区别）。如果两个部门的候选人不重合，那么要挑选3个人到这三个岗位一共有多少组合？

C7（1）*C10（2）=315 不好意思打不出排列组合的公式，希望看得懂

aggiesim · 发表于 2009-7-11 12:31:00

谢谢，明白了~

[求助]数学题真题 GIGI第一套上面的