8.设X1,X2,···,Xn是来自总体N(μ,σ^2 )的简单随机样本,X是样本均值,记 ({S)_(1)}^2=-|||-dfrac (1)(n-1)sum _(i=1)^n(({X)_(i)-overline (X))}^2 ({S)_(2)}^2=dfrac (1)(n)sum _(i=1)^n(({X)_(i)-overline (X))}^2, ({S)_(3)}^2=dfrac (1)(n-1)sum _(i=1)^n(({X)_(i)-mu )}^2, ({S)_(4)}^2=dfrac (1)(n)sum _(i=1)^n(({X)_(i)-mu )}^2,-|||-则服从自由度 n-1 的t分布的随机变量 = ()-|||-(A) dfrac (x-mu )({S)_(1)/sqrt (n-1)} (B) dfrac (x-mu )({S)_(2)/sqrt (n-1)}-|||-(C) dfrac (x-mu )({S)_(3)/sqrt (n-1)} ; (D) dfrac (x-mu )({S)_(4)/sqrt (n-1)}

设(X1,X2,···,Nn)是来自正态总体N (μ,σ^2)的-|||-简单随机样本,X是样本均值,记-|||-({S)_(1)}^2=dfrac (1)(n

设X1,X2,···,Xn是来自正态总体N(μ,σ^2)的简单随机样-|||-本,X是样本均值,记-|||-({S)_(1)}^2=dfrac (1)(n-1)

设X1,X2,···, _(n)(ngeqslant 2) 为来自总体N(μ,1)的简单随机样本,-|||-记 overline (x)=dfrac (1)(n

(8)设X1,X2,··· _(n)(ngeqslant 2) 为来自总体N(μ,1)的简单随机样本,记 overline (X)=dfrac (1)(n)su

(16)设X1,X2,···,xn为来自标准正态总体X的简单随机样本,记 overline (X)=dfrac (1)(n)sum _(i=1)^n(X)_(i

4.样本X1,X2,···Xn来自总体 sim N(0,1) , overline (X)=dfrac (1)(n)sum _(i=1)^n(X)_(i) ,

1.设X1,X2,···,xn来自总体X的样本, (X)=(sigma )^2, overline (X)=dfrac (1)(n)sum _(i=1)^n(X

设X1,X2,···, _(n)(ngt 2) 为来自总体N(0,1)的简单随机样-|||-本,X为样本均值,记 overline (X)=dfrac (1)(

[题目]设x1,x2,··, _(n)(ngt 2) 为来自总体N(0,1)-|||-的简单随机样本,x为样本均值,记 _(i)=(X)_(i)-overlin

3.设总体 approx N(mu ,(sigma )^2), X1,X2···Xn是来自该总体的简单随机样本,则-|||-dfrac (1)({sigma )