# What is the variance of z=2x+3y, in terms of the variances of x and y?

V(z) = V(2x + 3y) = ${2}^{2}$ $\times$ V(x) + ${3}^{2}$ $\times$ V(y) = 4V(x) + 9V(y)
V[ax + by] = ${a}^{2}$ V(x)+ ${b}^{2}$ V(y) is the formula employed.