PP-T2-PS25

[Huang Hsin-Yi]

25. 3619-!-item-!-187;#058&003382
A fast-food company plans to build 4 new restaurants. If there are 12 sites that satisfy the company's criteria for location of new restaurants, in how many different ways can the company select the 4 sites needed for the new restaurants if the order of selection does not matter?

(A) 48
(B) 288
(C) 495
(D) 990
(E) 11,880

Ans:C

感覺題目是問C(12,4)=11880,但是錯了,不知是那裡?

[bezoeca]

if the order of selection does not matter?
題目已經說排序不重要
先後順序在本題是不用考慮的
(12*11*10*9)/(4*3*2*1)
希望我寫得你了解

[Huang Hsin-Yi]

你的式子,也是C(12,4)的公式算出來
搞半天是我粗心
真是拍細!拍細!