For two independent variables X and Y we have VarX 12 VarY

For two independent variables, X and Y, we have Var(X) = 12, Var(Y) = 17. Find Var(4X – Y).

Solution

For two independent variables, X and Y, we have Var(X) = 12, Var(Y) = 17. Find Var(4X – Y).

since X and Y are independent, we are using this formula: Var(aX-Y) = a² Var(X) + Var(Y)

Var(4X-Y) = 16 Var(X) + Var(Y)

=16*12+17

=209