Prep -T2 PS146

[小花]

146. 14067-!-item-!-187;#058&010315
In a certain group of 10 members, 4 members teach only French and the rest teach only Spanish or German. If the group is to choose a 3-member committee, which must have at least 1 member who teaches French, how many different committees can be chosen?

(A) 40
(B) 50
(C) 64
(D) 80
(E) 100

Ans: E
題目沒給Spanish 和 German確定的數字
該如何求呢?

[amazingslim]

1個french: 4*C(6,2)=60
2個french: C(4,2)*6=36
3個french: C(4,3)=4

合計100

[小花]

謝謝amazingslim大大的回覆

[souljazz]

這裡提供另一個算法, C(10,3)-C(6,3)=120-20=100