Final answer:
To check the watch, quarter, and station bill at a prescribed interval, you should check every 4 hours.
Step-by-step explanation:
To check the watch, quarter, and station bill at a prescribed interval, you need to know the time intervals involved. Since a quarter is equal to 15 minutes and there are 4 quarters in an hour, checking every 15 minutes or every hour would be too frequent. Checking every 2 hours or every 6 hours would be too infrequent. Therefore, the best option is to check the watch, quarter, and station bill every 4 hours.