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)_(2)+dfrac (1)(2)(x)_(3) 是未知参数-|||-μ的无偏估计,则 b= __ -

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)+

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)_(

x1，x2是取自总体N(μ，1)(μ未知)的样本。hat (mu )_(1)=dfrac (2)(3)(X)_(1)+dfrac (1)(3)(X)_(2) ;

4.设总体 sim N(mu ,(sigma )^2), x1,x2,···,xn为样本,证明 overline (x)=dfrac (1)(n)sum _(i

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)

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,···

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)

[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

9.设总体 sim N(mu ,(sigma )^2) ,X1,X2,···,Nn为来自X的样本.-|||-证明:统计量-|||-.=dfrac ((dfrac

4.设X1,.,Xn为正态总体 sim N(mu ,(sigma )^2) 的样本,记 ^2=dfrac (1)(n-1)sum _(i=1)^n(({X)_(