Example 1 A petrol pump serves on the average 30cars per hour. Find the probability that during a period of 5 minutes (i) no car comes to the station, (ii) exactly 3 cars come to the station and (iii) more than 3 cars come to the station.

Average arrival = 30 cars/hr

                         = ½ car/min

Probability of no car in 5 minutes