10.设总体 sim N(mu ,(sigma )^2) ,X1,X2,X3是来自X的样本,则当 a= __ _时, mu =dfrac (1)(7)(X)_(1)+a(X)_(2)-|||-.+dfrac (4)(7)(X)_(3) 是未知参数μ的无偏估计.

4.设总体 sim N(mu ,(sigma )^2), x1,x2,x3为来自X的样本 hat (mu )=dfrac (1)(4)(x)_(1)+b(x)_

设sim N(mu ,1), X1、X2、X来自总体样本, hat (mu )=dfrac (2)(5)(X)_(1)+dfrac (2)(5)(X)_(2)+

多选题设总体sim N(mu ,(sigma )^2) X1,X2,···Xn为来自总体X的样本,sim N(mu ,(sigma )^2) X1,X2,···

10.设总体 sim N(0,1), X1,X2,X3是来自X的样本,则 =dfrac (sqrt {3)X}(sqrt {{{X)_(1)}^2+({X)_(

[题目]设总体 approx N(mu ,1), (x1,x2,x3)为其样本,-|||-若估计量-|||-mu =dfrac (1)(2)(x)_(1)+df

4.设总体 sim N(mu ,(sigma )^2) ,(X1,X2,···,Xn)为来自总体X的一个样本,X为样本均-|||-值,则 ()-|||-(A)

设(X1,X2,···,Xn )为来自正态总体 (mu ,(sigma )^2)设(X1,X2,···,Xn )为来自正态总体 (mu ,(sigma )^2)

设X1,X2,···X16为来自总体 sim N(2,(sigma )^2)设X1,X2,···X16为来自总体 sim N(2,(sigma )^2)（

样本X1,X2,X3来自总体X,若 hat (mu )=dfrac (1)(3)(X)_(1)+-|||-(X)_(2)+dfrac (1)(2)(X)_(3)

5.设x1,x2,···,xn是来自总体 sim N(mu ,(sigma )^2) 的样本,x为样本-|||-均值,令 =dfrac (sum _{i=1)^