5.10. 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 7:05 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 proportion of time does he or she go to destination A