Since the clock is 15 minutes slow and shows 3:45 and the actual time is a quarter past an hour, the correct time is likely 4:00 or 4:15. However, since the clock is 15 minutes behind the actual time, there is a mismatch in the information provided. The text suggests two possible times: 3:45 + 15 minutes (35 minutes) and a quarter past an hour. Please provide additional information or clarify the text for better assistance.