A variation on a familiar theme: A packet is received correctly by an end user with probability p. To increase the likelihood that an important message is received, the packet is sent repeatedly N times. Let random variable X be the number of copies received correctly by the end user. a) Find the PMF Px(x). b) If p = 0.9, how large should N be to ensure that with probability 0.99 at least one copy of the message is received?