单项选择题
A.均值 B.均值加3倍标准差 C.0.95分位数 D.中位数
A.N(20,0.152) B.N(20,0.0152) C.N(20,152) D.N(20,1.52)
A.1/81 B.16/81 C.65/81 D.80/81