Each hour, vehicles pass a certain point on a highway in accordance with a Poisson distribution. The expected number of vehicles that pass during the hour is four. Assume that one half of all passing vehicles are trucks, and one quarter are sports cars. Find the probability that, in a given hour, the passing vehicles include exactly two trucks and exactly one sports car. There is no restriction on the number of vehicles other than trucks and sports cars (so, for example, the event of two trucks, one sport car and seven other vehicles would satisfy the given condition).