NO.PZ2018062002000049
问题如下：
Benedict, an analyst from an investment company, recently gathered the following data for a price-weighted index comprised of securities G,H,I:
What is the price return of the index over the period?
选项：
A.
3.45%.
B.
7.1%.
C.
21.4%.
解释：
A is correct.
The sum of prices at the beginning of the period is 87; the sum at the end of the period is 90. Regardless of the divisor, the price return is , is calculated as the table below.
考点：价格加权指数计算price return
1、股票数量在这里用不到是迷惑你的（市值加权的指数才需要）
2、price-weighted index价格加权指数，假设每只股票买一股。price return是不考虑期间收益的收益率，本题也没有给出红利的信息，所以本题没有在这里设陷阱。
3、上课讲的方法是先分别计算期初和期末平均价格，再相除计算收益率，因为分母3可以约掉，所以上课的方法和解析的方法得到的结果是一样的。
这道题如果用课上讲的方法是怎么做呢
