求助各位数学大侠们数学GWD-3-18题，已经搜过了，没有解答

kirnamilk

大侠们指点一下一战因为数学失败的孩子吧，二战只有几天了...多谢啦！

Q18:

Last year the price per share of Stock X increased by k percent and the earnings per share of Stock X increased by m percent, where k is greater than m.  By what percent did the ratio of price per share to earnings per share increase, in terms of k and m?

A.   k/m %

B.    (k-m) %

C.   [100(k-m)]/(100+k) %

D.   [100(k-m)]/(100+m) %

E.    [100(k-m)]/(100+k+m) %

题目就不是很懂...

Answer是D~求解释！

jiuweilinghu

假设去年初始price per share=a, earnings per share=b；则，增长后今年price per share变成 a(1+k/100), earnings per share 为 b(1+m/100) - 注意k,m均为百分比，故要分别处以100处理；
题目问你：增加后price per share/earnings per share的增长率：
个么就是 {[a(1+k/100)]/[b(1+m/100)]-a/b}/(a/b)
前面{}括号里的是分子，/后(a/b)部分是分母
最后，因为问你是百分比，再乘以个100就是啦~
             

jiuweilinghu

我的公式的格式真难看=。=lz自己化一下~

kirnamilk

感谢jiuweilinghu同学！