A certain company sends 40% of its overnight mail parcels by means of express mail service A1. Of these parcels, 4% arrive after the guaranteed delivery time. Suppose that 50% of the overnight parcels are sent by means of express mail service A2 and the remaining 10% are sent by means of A3. Of those sent by means of A2, only 1% arrived late, whereas 5% of the parcels handled by A3 arrived late. (a) What is the probability that a randomly selected parcel arrived late