Let X be a random variable with the following probability distribution. Value x of X P(X=x) 10 0.25 20 0.30 30 0.05 40 0.40 Complete the following. (If necessary, consult a list of formulas.) (a) Find the expectation E (X) of X. E(X) = 2 X ? (b) Find the variance Var(X) of X. Var (X) = 2