小数点后几位偏差真的很多

问题如下：

The table below shows the monthly stock returns of Ivy Corp.

According to the above table ,calculate the mean absolute deviation for Ivy Corp. returns?

选项：

15.0%.

7.0%.

25.0%.

解释：

B is correct

The mean of returns=(20%+4%-5%+12%+3%+12%)/6=7.7%.

The mean absolute deviation can be calculated as ( |20-7.7| + |4 - 7.7| + |-5 - 7.7| + |12 - 7.7| + |3 - 7.7| + |12 - 7.7|) / 6 ≈ 7.0%.