一道2年级数学题 10人做9人错，答不对不太适合玩股

三十以后

说97的，进top 10

说100的，进top 20

说200或者197的，对不起，请重修小学文凭

gangrenboqi

以下是引用px100在2008-1-23 17:21:00的发言：

I heard that there also has one question, about if a stock price goes down 20%, what is the increase percentage to goes back?

 1. Define the price of this stock was A before it goes down. 

2. After the price goes down 20%, the latest price is: A*(1-20%).

3. To goes back to price A, the increase percentage should be: A-[A*(1-20%)]/A*(1-20%) = 25%

    

So, 'Danger in stock market, caution on boarding'