GWD5-Q3

amigos

Q3:

If a committee of 3 people is to be selected from among 5 married couples so that the committee does not include two people who are married to each other, how many such committees are possible?

A.     20

B.     40

C.     50

D.     80

E.      120

不会做，请nn指导～～～谢先～～～

答案是D

seinfeld0923

1. 先从5对夫妇中选出3对,C5,3. 然后对这三对中各选一个,2*2*2. 一共是C5,3*2*2*2=80

xp635

c10,3-c5,1*c8,1=80

boussoler

C10,3 - C5,1*C8,1 = 80

总的10人中取3人，然后再减去包含1对人的，也就是5对人里任选1对（C5,1）然后另一人再从剩下的8人里选（C8,1）