PP第一次模拟错了好多~~只能在这求救一道数学题

carvinhuang

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 those who received a P,40%  were females

(2)  of those who received an F or I, 80% were males.

答案是E
问题：
为什么答案不是C？两条件结合求不出吗？？

crown48

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 those who received a P,40%  were females

(2)  of those who received an F or I, 80% were males.

答案是E
问题：
为什么答案不是C？两条件结合求不出吗？？

-- by 会员 carvinhuang (2011/2/10 18:07:29)

0.4x+0.8(y+z)这个整体除以（x+y+z）

我这也是问版上的同学的
自己当时也错了

carvinhuang

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 those who received a P,40%  were females

(2)  of those who received an F or I, 80% were males.

答案是E
问题：
为什么答案不是C？两条件结合求不出吗？？

-- by 会员 carvinhuang (2011/2/10 18:07:29)

0.4x+0.8(y+z)这个整体除以（x+y+z）

我这也是问版上的同学的
自己当时也错了

-- by 会员 crown48 (2011/2/10 19:56:39)

carvinhuang

噢~~~你的XYZ就是P F I 吧？？

应该是这样列式吧？？0.4P+0.2(F+I)/(P+F+I)   ????