gwd28-37 (total-31)

[imfufu]

Q37:
In a meeting of 3 representatives from each of 6 different companies, each person shook hands with every person not from his or her own company. If the representatives did not shake hands with people from their own company, how many handshakes took place?

A. 45
B. 135
C. 144
D. 270
E. 288

the answer is (B) why not (A)?? thanks

[GOBLIN]

18*15/ 2

全部十八個人
每個人分別跟15個人握手
再除以二 因為握手是互相 不能DOUBLE COUNT

HOPE YOU UNDERSTAND

[christinehsu]

請大家 幫忙檢查一下我的思路
先謝謝了

我的作法是
因為不能與自己公司的人握手，所以第一步為在六個公司中取兩個公司握手。
因為每個公司中各有三個人，所以在取出的兩個公司中的三個人，各挑一人出來握手。
因此，
C6取2 *C3取1*C3取1=135