Let X be a random variable with the following probability distribution. Value x of X P(X-x) -30 0.35 -20 0.25 -10 0.05 0 0.35 Complete the following. (If necessary, consult a list of formulas.) (a) Find the expectation E (X ) of X. E( X) = 1 X ? (b) Find the variance Var(X) of X. Var (X) =