A file consisting of X packets is sent over the network to an end user. It is known that X is a random variable with PMF PX(x) = cx2 for x = 1, 2, 3, 4; and PX(x) = 0 otherwise. Each packet is received correctly with probability p, independently of the other packets. a) Find the constant c. b) Find P[X > 2]. c) Find the probability that the entire file is received correctly, i.e., all X packets are received correctly