[計量] pp1 ps43
43.A committee of three people is to be chosen from four married couples. What is the number of different committees that can be chosen if two people who are married to each other cannot both serve on the committee?
(A) 16
(B) 24
(C) 26
(D) 30
(E) 32
答案 E
我知道是C(8,3)-4*6
可是我想知道我的笨想法為什麼行不通
我想成四對couple總共有八個人
選第一個人 可以從八個人挑
選第二個人 只剩下六個人可以挑 (因為要去除第一個被挑走的人的另一半)
選第三個人 只剩下四個
8*6*4 誰能點醒我為什麼這樣想不對嗎??
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