Let x = the time between two successive arrivals at the drive-up window of a local bank. if x has an exponential distribution with λ = 1, (which is identical to a standard gamma distribution with α = 1), compute the following. (if necessary, round your answer to three decimal places.)

(a) the expected time between two successive arrivals 1
(b) the standard deviation of the time between successive arrivals 1
(c) p(x ≤ 2) 0.865 (d) p(3 ≤ x ≤ 5) .043