babypace暂别G

babypace

在tania他们后面。没有信心。

wwwhahchn

顶顶baby的帖子

加油哦，我们都还在，所以你并不孤单

babypace

en. 谢谢。

问道题。

If a committee of 3 people is to be selected from among 5 mattied couples so that the committtee does not include two people who are married to each other, how many such committees are possible?

answer is 80.

今天脑子不太好使，想不出来怎么排的，算半天480。

babypace

还有一个。

If the number 52,1n9 where n represents the tens digit, is a multiple of 3, then the value of n could be which of the following?

answer is 5. but I got 1.

confusing....

linda05312

以下是引用babypace在2005-9-21 0:39:00的发言：

en. 谢谢。

问道题。

If a committee of 3 people is to be selected from among 5 mattied couples so that the committtee does not include two people who are married to each other, how many such committees are possible?

answer is 80.

今天脑子不太好使，想不出来怎么排的，算半天480。

baby J, 这道题你看是否可以这样考虑：

C(3,5)*C(1,2)*C(1,2)*C(1,2)

首先从5对夫妇里选出3对，然后每对里有两种可能。

esprit

以下是引用babypace在2005-9-21 0:39:00的发言：

en. 谢谢。

问道题。

If a committee of 3 people is to be selected from among 5 mattied couples so that the committtee does not include two people who are married to each other, how many such committees are possible?

answer is 80.

今天脑子不太好使，想不出来怎么排的，算半天480。

C10，3-C5，1*C8，1=80

A〉10个人任取3个-----C10，3减去其中有夫妻的组合

B〉有夫妻的组合：1〉5对夫妻任取1对---C5，1

                          2〉剩余8个人任取1个人----C8，1

A-B即为所求。

ProteinMonica

怀疑后面那一道答案错？

[此贴子已经被作者于2005-9-21 1:32:53编辑过]

linda05312

tonggan

babypace

thanks Linda and esprit. I got it now. both way works fine.

I agree with you guys on the 2nd one. I can't understand why the answer is 5. It's so obvious that the answer should be 1.

tania

同意baby的意见，应该是1，也许是jj作者记错了具体的数字，没关系，只要掌握做法就好拉

baby没问题的，我们都支持你！！