问题如下：
An analyst gathers the following data for an equally-weighted index:
The return on the index over the period is:
选项：
A. 4.2%.
B. 6.8%.
C. 7.1%.
解释：
C is correct.
With an equal-weighted index, the same amount is invested in each security. Assuming $1,000 is invested in each of the three stocks, the index value is $3,000 at the beginning of the period and the following number of shares is purchased for each stock:
Security A: 50 shares
Security B: 20 shares
Security C: 38.46 shares.
Using the prices at the beginning of the period for each security, the index value at the end of the period is
$3,213.8: ($22 × 50) + ($48 × 20) + ($30 × 38.46). The price return is $3,213.8/$3,000 – 1 = 7.1%.
我实在是不明白了，为什么equal-weighted有的题目是用算数平均，有的用几何平均，看题目也没什么区别啊，比如pz2015122802000043就是几何平均