GWD 9-36

nolanchen · 发表于 2006-6-30 15:16:00

If x, y, and k are positive numbers such that (x/(x+y))(10) + (x/(x+y))(20) = k and if x < y, which of the following could be the value of k?

A. 10

B. 12

C. 15

D. 18

E. 30

Answer: D

我觉得A和B都对,但D不对。例如A答案当x=1，y=2，k=10代入式中，是满足上述等式的；同理B答案当x=2，y=3，k=12代入式中，也是满足上述等式的。为什么答案选D？

hitlzc · 发表于 2006-6-30 18:09:00

我记得看到过这道题是 (x/(x+y))(10) + (y/(x+y))(20)= k

mit2007 · 发表于 2006-7-1 03:48:00

嗯。应该是y。答案是18

所属分类: GMAT考试