Trains headed for destination A arrive at the train station at 15-minute intervals starting at 7 A.M., whereas trains headed for destination B arrive at 15-minute intervals starting at 7:10 A.M. (a) If a certain passenger arrives at the station at a time uniformly distributed between 7 and 8 A.M. and then gets on the first train that arrives, what is the probability that he or she goes to destination A? (b) What if the passenger arrives at a time uniformly distributed between 7:10 AM and 8:15 AM?