130.设x1,x2,x1,x..........Ym分别来自点体N (μ1,σ1^2)和N(μt2,σ2),它们相互独立,且-|||-({S)_(n)}^2=dfrac (1)(n-1)sum _(i=1)^n(({X)_(i)-X)}^2 ({S)_(m)}^2=dfrac (1)(m-1)sum _(i=1)^m(({r)_(i)-Y)}^2, 则 =dfrac ({{S)_(n)}^2}({{S)_(m)}^2}cdot dfrac ({{sigma )_(2)}^2}({{sigma )_(1)}^2}sim __ _。

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,···,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,···,Xn, _(n+1) 是来自正态总体N(μ,σ ^2)的样本,设X1,X2,···,Xn, _(n+1) 是来自正态总体N(μ,σ ^2)

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

5.11 设(X1,X2,···Xn, _(n)+1) 是正态总体N(μ,σ^2)的样本, overline (X)=-|||-dfrac (1)(n)sum

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

若X1,X2,···, _(n)(ngeqslant 2)为来自总体X1,X2,···, _(n)(ngeqslant 2)的简单随机样本,X1,X2,···,