4.设随机变量 sim N(1,9) , sim N(0,16) ,相关系数 (rho )_(xy)=-dfrac (1)(2) ,设-|||-.=dfrac
已知随机变量( X ,Y) 服从二维正态分布,且 X 和Y 分别服从正态分布N(1,3^2)和-|||-N(0,4^2),X与Y的相关系数 (rho )_(x
已知随机变量X-N(1,9) ,Y~N(0,16),它们的相关系数为-dfrac (1)(2),设-dfrac (1)(2),则-dfrac (1)(2)( )
29.设随机变量 sim N(1,9), sim N(0,16), 且X与Y的相关系数为 (rho )_(xy)=-0.5, =dfrac (1)(3)X+df
3.设 approx N(0,(4)^2), approx N(1,(3)^2), 且 (rho )_(x)=-dfrac (1)(2), 令 =dfrac (
设随机变量X,Y满足P(XY=0) =1,并且分布律分别为X -1 0 2 Y 0 1-|||-P dfrac (1)(6) dfrac (1)(3) dfra
18.设随机变量X,Y满足 E(X)=1 D(X)=1 E(Y)=2 D(Y)=4 ,(rho )_(xy)=0.5 ,-|||-令 =dfrac (X)(2)
设随机变量X~N(0,1),Y~N(1,4),且 rho_(XY)=-(1)/(2),设 Z=(1)/(3)X+(1)/(2)Y,则D(Z)=()A. 7/9B
已知 approx N(1,(3)^2), backsim N((0.4)^2), 且X与Y的相关系数 rho =-1/2, 设 =dfrac (x)(3)--
设有随机变量X,Y,Z,已知EX=1, EY=2,EZ=-1,DX=1,DY=2,DZ=3,且rho xY=0,, rho xz=dfrac (1)(2), r