Let X1,X2,X3 be jointly distributed with means 1=2,2=5 and 3=2 and varaince-covariance matrix =4xyx60y04 here x and y are constants. Let Z1=X1+2X24X3 and Z2=X1+X2+X3, determine (i) E[Z],Z=(Z1,Z2) (ii) the values of x and y such that Z1 and Z2 are independent and Var(Z2)=10. Hence find the mean and variance of Z=2Z1+5Z24