数学两道 不会

guo573874201

1. In a corporation, 50 percent 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正确
E.5/6

2.What is the median number of employees assigned per project for the projects at Company Z?

(1)25 percent of the projects at Company Z have 4 or more employees assigned to each project.

(2) 35 percent of the projects at Company Z have 2 or fewer employees assigned to each project.答案是C  



小弟求具体的思路

wyw1018

1, 0.5m+0.4f=0.42(m+f)-->m=1/4f-->f/(m+f)=f/(1/4f+f)=4/5
2,由1，2可知有40%的projects分配的员工大于2小于4，由于员工不能为小数，所以就是3，处于50%-51%之间的projects只能是3个员工