NO.PZ2022123001000023
问题如下：
A portfolio manager invests €5,000 annually in a security for four years at the prices shown in the following exhibit.
The average price is best represented as the:
选项：
A.
harmonic mean of €76.48
B.
geometric mean of €77.26
C.
arithmetic average of €78.00
解释：
The harmonic mean is appropriate for determining the average price per unit. It is calculated by summing the reciprocals of the prices, then averaging that sum by dividing by the number of prices, then taking the reciprocal of the average:
4/[(1/62.00) + (1/76.00) + (1/84.00) + (1/90.00)] = €76.48.
如题，为什么不能用算数平均，而用调和平均？
