题目
1.设总体 sim N(M,(sigma )^2) ,μ未知而σ^2已知,X1,X2,···,Xn是X的样本, overline (X)=dfrac (1)(n)sum _(i=1)^n(X)_(i) --|||-.^2=dfrac (1)(n-1)sum _(i=1)^n(({X)_(i)-overline (X))}^2 ,则以下为统计量的是 ()-|||-A. dfrac (1)({sigma )^2}sum _(i=1)^n(({X)_(i)-mu )}^2 B. dfrac (1)({sigma )^2}sum _(i=1)^n(({X)_(i)-overline (X))}^2 C. dfrac (overline {X)-mu }(sqrt {{sigma )^2/n}} D. dfrac (overline {X)-mu }(sqrt {{s)^2/n}}
题目解答
答案
1.D 解析：统计量的分布需要满足 E(Y)=常数, 即 $E(Y)=E(\dfrac {\overline {X}-\mu }{\sqrt {{S}^{2}/n}})=\dfrac {E(\overline {X}-\mu )} {\sqrt {{S}^{2}/n}}=0$ 成立, 故选D.
1.D
1.D