问一道Prep的DS，谢谢阿！！

gfwindy

each of the students in a certain class received a single grade of P、F or I, what percent of the students in the class were females?

(1)of who received a P,40% are females

(2)of those who received either an F or I, 80% are males

我选C的，但是答案是E，求牛人指教！谢谢！

gfwindy

自己顶一下，谢谢指教！

wawadream

主要问题是两选项都没有给出P,F,I占总人数的比例。

the percent of the female=P*40%+(F+I)*20%

if the amount of P,F,Ichanged,the female percent would change accordingly.