[問題] Form19 Sec5-Q20

[sam6521]

On a certain test , a student must select 3 out of 6 questions to answer. What is the total number of different combinations of 3 questions that the student can select?

(a)10
(b)12
(c)15
(d)18
(e)20

Ans:(e)

Q:組合(ex:ABC及ACB)應該不能重覆計算,所以答案應該是(a)嗎?

[navywhite0425]

c(6,3)=20