No links please

No links please Let x and y be two independent random variables variances k and 2 respectively. If the variance of z: 3y-x be 25, find k.

Dear Student ,

z = 3 y - x Var (z) = Var (3 y - x) 25 = 3^{2} Var (y) + Var (x) (Since Var (ax - y) = a^{2} Var (x) + Var (y)) 25 = 9 (2) + k 25 = 18 + k k = 7 ANS . . .

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