Let X be a random variable with the following probability distribution. Value x of X P(X=x) -30 0.05 -20 0.10 -10 0.20 0 0.50 10 0.05 20 0.10 Complete the following. (If necessary, consult a list of formulas.) (a) Find the expectation E(X) of X. E (X) = [] (b) Find the variance Var(X) of X. Var(x) =