- UID
- 1372342
- 在线时间
- 小时
- 注册时间
- 2018-11-9
- 最后登录
- 1970-1-1
- 主题
- 帖子
- 性别
- 保密
|
大神这个数学题最后选了什么啊?
我今天做了一道类似的题
From a group of 8 volunteers, including Andrew and Karen, 4 people are to be selected at random to organize a charity event. What is the probability that Andrew will be among the 4 volunteers selected and Karen will not?
A. 3/7
B. 5/12
C. 27/70
D. 2/7
E. 9/35
We need Andrew and 3 others but not Karen in the group. The # of ways to choose 3 members out of 8-2=6 (all but Andrew and Karen) is C36, thus P=C36/C48=2/7
https://gmatclub.com/forum/from-a-group-of-8-volunteers-including-andrew-and-karen-160883.html
按这个思路的话这题是得C72/C310=7/40么? |
|