Z~N(0,1), Let X1=Z, X2=Z^2, find cov(X1,X2).

Cov(X1,X2)= E(X1*X2)-E(X1)E(X2)= E(Z^3)-E(Z)E(Z^2)= E(Z^3)

bcoz E(Z)=0, does it mean E(Z^n)=0 ??? anyone can explain ?? thanx

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- Nov 22nd 2008, 06:11 PMsolskjaera question abt covariance
Z~N(0,1), Let X1=Z, X2=Z^2, find cov(X1,X2).

Cov(X1,X2)= E(X1*X2)-E(X1)E(X2)= E(Z^3)-E(Z)E(Z^2)= E(Z^3)

bcoz E(Z)=0, does it mean E(Z^n)=0 ??? anyone can explain ?? thanx - Nov 22nd 2008, 07:59 PMmr fantastic