computational statistics

a. A random variable X has the following probability distribution: X 0 x 488 5 x 488 10 x 488 15 x 488 20 x 488 25 x 488 P(X = x) 0.1 0.2 0.1 0.04 0.07 a. Find the value of n. b. Find the mean/expected value E(x), varianceV(x) and standard deviation of the given probability distribution. c. Find E(-4A x + 3) and V(6B x - 7)