Y1 (1) Let Y 2 Y2 be a random vector mean expected value and covariance matrix Y3 1 1 1 (J ,u. : 1 . E : 1 2 3 3 0 3 10 (a) Let Z : 2Y1 3Y2 + Y3. Find 41(Z). Find Var(Z) in two different ways: via a direct expansion using varianceweovariancc calculation rules, and by matrix calculation. (b) Let Z 21 _ 22 q where 21 2 Y1 + Y2 + Y35 and Z2 2 3Y1 + Y2 2Y3. Find 113(2) Find Cov(Z) in two different ways: via a. direct expansion using varianee-covariance calculation rules, and by matrix calculation