.-(x)^2(n) 的简单随机样本, overline (X)=dfrac (1)(n)sum _(i=1)^n(X)_(i) ,则-|||-|E(overline (X)),D(overline (X))|= ()().-|||-A (n.2n);-|||-B (2.n);-|||-C (n.2);-|||-D (2n.n)

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

(B) dfrac (1)(n+1)sum _(i=1)^n(({X)_(i)-overline (X))}^2 .-|||-(C) dfrac (1)(n)s

(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

7.设X1,X2,···, _(n)(ngeqslant 2) 为来自正态总体N(μ,1)的简单随机样本,若 overline (X)=-|||-dfrac (

dfrac (1)(n-1)sum _(i=1)^n(({X)_(i)-overline (X))}^2 .-|||-n-|||-C. sqrt (dfrac

设总体 X sim N(mu, sigma^2), X_(1), X_(2), ..., X_(n) 为来自总体X的简单随机样本，则 sum_(i=1)^n((

设X_1, X_2, ..., X_n是取自总体X的一个简单随机样本，则（） overline(X) = EX E(overline(X))= EX ov

4.设X1,X2,···,Xn为来自正态总体 sim N(0,1) 的简单随机样本, overline (X)=dfrac (1)(n)sum _(i=1)^n

=2-|||-4.设X1,X2,···,x3是来自总体 approx N(1,4) 的简单随机样本, overline (X)=dfrac (1)(n)sum