求助 GMATPREP2里的一道平均数的DS题

小小圆子

At a certain company, the average (arithmetic mean) number of years of experience is 9.8 years for the male employees and 9.1 years for the female employees.  What is the ratio of the number of the company's male employees to the number of the company's female employees?  
(1)  There are 52 male employees at the company.  
(2)  The average number of years of experience for the company's male and female employees combined is 9.3 years.

选B

我选了E，不明白 2 ）？ 因为 a+b 的平均数≠ a平均数+b平均数，无法得出有用的信息。

-----
233333 就在我打出这些字的时候，突然就想通了

2）因为求得是比例，不是具体数值，设男员工为M个，女员工为W个
(9.8M+9.1W)/(M+W)=9.3
9.8M+9.1W=9.3M+9.3W
∴M/W=2/5
所以B
------
既然打出来了就分享给你们吧，像我这样自问自答的估计不多了。。。

德州小霸王

设male employees占X%
那么female employee就是(1-x%)

根据B： x%*9.8+(1-x%)9.1=9.3
X只有一个答案 可以算出人数比例哦