[求助]数学JJ一道

sarahhy

   不好意思，又来请教了。
   From the beginning of the last year, price per share increased K percent,Eaning per share increased M percent.Question:ask the ratio in percentage for price per share to eaning in incease . In term of K and M .
   我太懂这题目的意思，可能是我理解错了，我怎么都的不出JJ给出的答案：（K-M)/(100+M)
请问推理的是怎样的。多谢！！[em12][em12][em12][em02][em02][em02]

maryland

[思路] price per share increased K percent, earning per share increased M percent,其中的 K% 和 M% 指的是今年比去年增长的比率。
       今年price=X（1+k%）  
       今年earning=Y（1+m%）
       求的是price/earnings比例的增长：
       [X(1+k%)]/ [Y(1+m%)]-(X/Y)=(K-M)/(100+M)

GOT IT? [em23]

sarahhy

Tank you! I got it.