If we are only concern about the longer hand (minute hand) of the clock, then we can say:
3:55 PM to 4:55 PM => 360° or π radians
because it's one hour. So to answer the question, 3:55 pm to 4:40 pm is 15 minutes less than an hour, which is 45 minutes or 3 quarters of an hour. Therefore:
3:55 PM to 4:40 PM => (3/4)π radians