Question 604855
Variance


sigma^2 = Sum( P(X = xi) * (xi - E(X) )^2 )


sigma^2 = [0.3*(-4 - 0.8)^2] + [0.2*(0 - 0.8)^2] + [0.5*(4 - 0.8)^2]


sigma^2 = [0.3*(-4.8)^2] + [0.2*(-0.8)^2] + [0.5*(3.2)^2]


sigma^2 = 0.3*23.04 + 0.2*0.64 + 0.5*10.24


sigma^2 = 6.912 + 0.128 + 5.12


sigma^2 = 12.16


So the variance is 12.16