Question

Consider a small post office with a single staff member operating a single postal
counter. Suppose that the probability pk, that there are k customers in the post
office, is given by pk = p0p^k k = 0,1,2,... where 0 < p < 1.
(a) Show that p0 = 1 - p.
(b) Determine the probability that a newly arriving customer has to wait to be
served.