Let N(t) be the number of accidents at a specific intersection in the interval [0,t]. We suppose that {N(t),t ≥ 0} is a Poisson process with rate λ1 = 1 per week. Moreover, the number Yk of persons injured in the Kth accident has (approximately) a Poisson distribution with parameter λ2 = 1/2, for all k. Finally, the random variables Y1Y2,... are independent among themselves and are also independent of the stochastic process {N(t) t ≥ 0}.
