math jj

flyingus

请教斑竹：

94. ds in the beginning of the year, there are n persons in A committee and n person in B committee and no people serve in both committees. in the end of the year, 1 person leave A committee and 3 persons leave B commitee. ask how many persons in the commitees in the beginning of the year?
a) the proportion of the number of people leaving at the end of the year to the number of people in the beginning of year is 1:12
b) there are 21 persons staying in B commitee at the end of the year.
[第一个条件 4：T=1：12 求得T=48，但不知道A，B中分别有多少，不充分，第二个
条件，只能知道B Committee在年初时有24人，但不知道A有多少。两个一起
就充分，都有24个人]

这题问的是“how many persons in the commitees”，并没有问A，B中分别有多少，好象选D吧？

６． 问１班的２０％＝２班的１３％？
ａ）１班人数＝６０％　ｏｆ　２班　ｂ）４０％１班＝
２８％２班 KEY: e

选D吧，否定也是回答，对吗？

5. ３个人两间屋，一堆条件如允许一件房子为空等，问几种
分法？８

这题什么意思？

Thanks a lot!