3.设X_(1),...,X_(10)为来自标准正态总体Xsim N(0,1)，Y_(1)=7sum_(i=1)^3X_(i)^2,Y_(2)=3sum_(i=4)^10X_(i)^2则(Y_(1))/(Y_(2))sim____.

3.假设X，X_(1)，X_(2)，…，X_(10)是来自正态总体N(0，sigma^2)的简单随机样本，Y^2=(1)/(10)sum_(i=1)^10X_(

设X_(1),X_(2),...,X_(10)是来自正态总体N(0,1)的简单随机样本，则统计量Y=(1)/(4)(sum_(i=1)^4X_(i))^2+(1

设（X_(1),X_(2),...,X_(10),X_(11)）是来自于正态总体Xsim N(mu,sigma^2)的样本，bar(X)=(1)/(n)sum_

X_(9)是来自总体X的样本，Y_(1),Y_(2),... Y_(9)是来自总体Y的样本，则统计量U=(X_(1)+...+X_(9))/(sqrt(Y_(1

2.设X与Y相互独立且都服从N(0,3²)分布，X_(1),X_(2),...,X_(9)，Y_(1),Y_(2),...,Y_(9)分别是来自 于X和Y的样本

37.已知x_{n)},y_{n)}满足：x_(1)=y_(1)=(1)/(2),x_(n+1)=sin x_(n),y_(n+1)=y_(n)^2(n=1,2

,X_(9) 与 Y_(1),Y_(2), ... ,Y_(9) 是分别来自动体X,Y的简单样本,统计量 W= (X_(1)+X_(2)+ ... +X_(9)

设 X_1, X_2, ldots, X_(10) 是来自正态总体 N(0,1) 的简单随机样本，则统计量 Y = (1)/(4)(sum_(i=1)^4 X_

22 （1）设随机变量X_(1),X_(2),X_(3),X_(4)相互独立，且有E(X_(i))=i,D(X_(i))=5-i,i=1,2,3,4.设Y=2X

若 Y=X_(1)+X_(2)，X_(i) sim N(0,1)，i=1,2，则（）A. $E(Y)=0$；B. $D(Y)=2$；C. $Y \sim N(0