Cars get parked in a lot (with infinite capacity) according to a λ-rate Poisson process, and independently stay parked for a random duration. The parking time duration of a car follows a common distribution X, with cdf F(x) = P(X ≤ x). Let N(t) be the number of cars parked at time t.
1a. What is the distribution of N(t)?
1b. Assuming a car arrival rate of 1 per minute, and X (in min) ∼ Gamma(3, 1) (as defined in class), what is the expected number of cars parked after 1 hour?
2. In the long run (t → ∞), what is the expected number of cars, as a function of λ and the moments of X?