Requests for a product (information or service) arrive from m cities at times that form independent Poisson processes with rates λ1,...,λm. Given that there are n requests from the cities in the time...

Requests for a product (information or service) arrive from m cities at times that form independent Poisson processes with rates λ1,...,λm. Given that there are n requests from the cities in the time interval (0, t], find the conditional probability that n1 are from city 1 and n2 are from city 2.