Closing sales
A salesman normally makes a sale (closes) on 80% of his presentations. Assuming the presentations are independent, find the probability of each of the following.
a) He fails to close for the first time on his fifth attempt.
b) He closes his first presentation on his fourth attempt.
c) The first presentation he closes will be on his second at- tempt.
d) The first presentation he closes will be on one of his first three attempts.