The length of time, Y , that a customer spends in line
at a bank teller’s window before being served is described
by the exponential pdf fY (y) = 0.2e−0.2y , y ≥ 0.
(a) What is the probability that a customer will wait more
than ten minutes?
(b) Suppose the customer will leave if the wait is more
than ten minutes. Assume that the customer goes to
the bank twice next month. Let the random variable
X be the number of times the customer leaves without
being served. Calculate pX (1).