请教一道比例题

forgetviviva

 

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?

 

B.     (k – m) %

C.     [100(k – m)] / (100 + k) %

D.     [100(k – m)] / (100 + m) %

E.      [100(k – m)] / (100 + k + m) %

Answer: D

快考试了, 请nn们帮帮忙

miaoyin_tx

這是我的解法，供你參考看看囉!!

設the price per share of Stock X 為P

 the earnings per share of Stock X為E

原始the ratio of price per share to earnings per share 就為P/E

當P增加k%，E增加m%， 則the ratio of price per share to earnings per share increase變為P(1+k%)/E(1+m%)

By what percent did the ratio of price per share to earnings per share increase就等於{P(1+k%)/E(1+m%)-P/E}/P(1+k%)/E(1+m%)

化簡完就為

D.     [100(k – m)] / (100 + m) %

你看看~若不等再問我唷! 我很熱心為你解答的!!

forgetviviva

你好！ 谢谢你给了我思路 

我想通了

不过你的式子好像有点错误

{P(1+k%)/E(1+m%)-P/E}/P(1+k%)/E(1+m%)

红色部分应该是 P/E 才对