问题如下：
A mutual fund has the return frequency distribution shown in the following table.
Which of the following statements is correct?
选项：
A.The relative frequency of the interval "–1.0 to +2.0" is 20%.
B.The relative frequency of the interval "+2.0 to +5.0" is 23%.
C.The cumulative relative frequency of the interval "+5.0 to +8.0" is 91.7%.
解释：
A is correct.
The relative frequency is the absolute frequency of each interval divided by the total number of observations. Here, the relative frequency is calculated as: (12/60) × 100 = 20%. B is incorrect because the relative frequency of this interval is (23/60) × 100 = 38.33%. C is incorrect because the cumulative relative frequency of the last interval must equal 100%.
这道题不太理解，麻烦讲解下，谢谢。
