问题如下:
Determine the variance of a discrete uniform distribution, which is defined as X={2,4,6,8,10}.
选项:
A. 6.
B. 8.
C. 2.8.
解释:
B is correct
Expected value= (1/5)(2+4+6+8+10) = 6
Variance= (1/5)[(2-6)2 + (4-6)2+ (6-6)2 + (8-6)2+(10-6)2] = 8
请问这种题目怎么判断是样本还是整体呢?如果题目不说,一般当样本还是整体算呢?