GWd4/6-29 bu hui

LISAYUAN750616

GWD-4/6-29

If two copying machines work simultaneously at their respective constant rates, how many copies do they produce in 5 minutes?

(1)   One of the machines produces copies at the constant rate of 250 copies per minute.

(2)   One of the machines produces copies at twice the constant rate of the other machine.

why not D instead of E

The annual rent collected by a corporation from a certain building was x percent more in 1998 than in 1997 and y percent less in 1999 than in 1998.  Was the annual rent collected by the corporation from the building more in 1999 than in 1997?

(1)   x > y

(2)   xy/100 < x – y

bu hui

XIE XIE

linlin315

If two copying machines work simultaneously at their respective constant rates, how many copies do they produce in 5 minutes?

(1)   One of the machines produces copies at the constant rate of 250 copies per minute.

(2)   One of the machines produces copies at twice the constant rate of the other machine.

why not D instead of E

单独（1）只能知道一台机器5min produce多少copies，并不知道另外一台机器。

单独（2）只知道两个速度的关系并不知道具体值，所以也不可以

（1）和（2）结合也不行。

因为由（2）我们知道A=2B的关系，但是（1）中的250到底是A还是B我们并不清楚，因而得到的结果并不唯一。

综上：E

linlin315

The annual rent collected by a corporation from a certain building was x percent more in 1998 than in 1997 and y percent less in 1999 than in 1998.  Was the annual rent collected by the corporation from the building more in 1999 than in 1997?

(1)   x > y

(2)   xy/100 < x – y

根据题意我们可以得到如下的关系：

1997年设为a，1998  a(1+x%), 1999 a(1+x%-y%)

问：a(1+x%-y%)是否大于a，其实就是问x是否大于y

(1)可以

（2）x>y+xy/100--〉x>y

因而答案是D

LISAYUAN750616

ni zhen shi tai hao le.

i have little problem with the 1999 a(1+x%-y%) i asumme it is a(1+x%)(1-y%)

sorry to draw you so much attention.

lilyning

以下是引用LISAYUAN750616在2004-12-23 12:55:00的发言：

ni zhen shi tai hao le.

i have little problem with the 1999 a(1+x%-y%) i asumme it is a(1+x%)(1-y%)

sorry to draw you so much attention.

(1+x%)(1-y%)

I think you are right.

linlin315

以下是引用LISAYUAN750616在2004-12-23 12:55:00的发言：

i have little problem with the 1999 a(1+x%-y%) i asumme it is a(1+x%)(1-y%)

sorry for that! you are right!

linlin315

不过思路是一样的

LISAYUAN750616

xie xie le-all

jzzbeyond

这题是选B

(1+x%)(1-y%)

jingle0915

xie xie le-all