[問題]GWD 10-11

[法法]

再度麻煩大家~~
In a corporation, 50percent of the male employees and 40 percent of the female employees are at least 35 years old. If 42 percent of all the employees are at least 35 years old, what fraction of the employees in the corporation are females?
A 3/5
B 2/3
C 3/4
D 4/5
E 5/6
Ans:D

THANKS!!

[cheyen]

我是假設
全部的人(男+女)=X
女=Y

50percent of the male employees and 40 percent of the female employees are at least 35 years old.
If 42 percent of all the employees are at least 35 years old

(X-Y)*50% + Y * 40% = X * 42%

what fraction of the employees in the corporation are females?

就是指y/x

整理之前的式子
0.5x-0.5y+0.4y=0.42x

0.08x=0.1y

y/x =4/5

大家看看這樣可不可以
還是有別的作法
多多指教

[法法]

超清楚!THANKS!