(3)设X_(1)sim N(1,2),X_(2)sim N(0,3),X_(3)sim N(2,1),且X_(1),X_(2),X_(3)相互独立,则P0le
1 设总体Xsim N(0,1),X_(1),X_(2),...,X_(n)为X的样本,则((X_(1)-X_(2))/(X_(3)+X_{4)})^2服从__
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
已知随机变量X_(1), X_(2), X_(3)的协方差COV(X_(1), X_(3)) = 2, COV(X_(2), X_(3)) = 1。则COV(X
设X_(1),X_(2),...,X_(n)为总体Xsim N(mu,sigma^2)的样本,证明hat(mu)_(1)=(1)/(2)X_(1)+(2)/(3
x_(1)+x_(2)+x_(3)leq6,x_(1)+2x_(2)+4x_(3)geq12,x_(1)-x_(2)+x_(3)geq2,x_(2)geq0,x
设数列x_{n)}由x_(1)in(-infty,+infty)和x_(n+1)=(1)/(3)x_(n)+(2)/(3)-(1)/(2)int_(1)^x_(
设随机变量X_(1),X_(2)相互独立,X_(1)sim N(0,1),X_(2)sim N(0,2),下列结论正确的是()A. $X_{1}=X_{2}$B
7.设X_(1),X_(2),X_(3)是来自总体Xsim N(0,1)的一组样本,则X_(1)+X_(2)+X_(3):____,X_(1)^2+X_(2)^
简答题19、解线性方程组}x_(1)+x_(2)+x_(3)+x_(4)=1 x_(1)+2x_(2)-x_(3)+3x_(4)=2 2x_(1)+3x_(2)