Suppose, a telephone exchange becomes very busy at a certain time of the day which is known as a busy time where callers face difficulty placing their calls. Assume the probability of a connection in...

Suppose, a telephone exchange becomes very busy at a certain time of the day which is known as a busy time where callers face difficulty placing their calls. Assume the probability of a connection in the telephone exchange during the busy time is 0.07.

a) What is the probability that exactly 6 attempts are necessary for a successful call?

b) What is the expected number of successful calls during the busy time?