问题如下:
The table below shows part of the monthly stock returns of Ivy Corp.
Calculate the sample variance for Ivy Corp. returns, assuming above tabe inclues all samples?
选项:
A.8.78%.
B.64.2%2.
C.77.1%2.
解释:
C is correct
= [(20 - 7.7)2 + (12 - 7.7)2 + (-5- 7.7)2 + (12- 7.7)2 + (3 - 7.7)2 + (12- 7.7)2] / (6-1) = 77.1%2
include all samples,不是应该按照总体来算嘛?为什么是按照样本来算的。
以后遇到类似问题,应该怎么判断他让我们用总体,还是样本计算?