Step-by-step Solution:

Quick Solution

This is a clock puzzle that requires us to first translate the angular position of the hour hand into specific times of the day, and then calculate the duration of the trip.

1. Convert the Hour Hand's Angle to a Time Duration

• The hour hand of a clock moves a full circle (360°) in 12 hours (or 720 minutes).
• Its speed is therefore 360° ÷ 720 minutes = 0.5° per minute.
• The problem states the hour hand was 20° away from the '4' mark. To find how much time this angle represents, we calculate:
  Time = Angle ÷ Speed = 20° ÷ (0.5° per minute) = 40 minutes.

This means the two times Jimmy saw the clock were 40 minutes before 4:00 and 40 minutes after 4:00.

2. Determine the Start and End Times of the Trip

• Time 1 (When going): 40 minutes before 4:00 is 3:20.
• Time 2 (When returning): 40 minutes after 4:00 is 4:40.

3. Calculate the Time Spent at the Tennis Court

• The total time that passed from when he left to when he returned is the difference between these two times:
  4:40 - 3:20 = 1 hour and 20 minutes = 80 minutes total.
• This 80-minute duration includes the time it took to travel to the court and back.
• Travel time to the court = 10 minutes.
• Travel time returning = 10 minutes (since the speed and distance were the same).
• The time spent at the court is the total duration minus the travel time:
  Time at court = (Total Duration) - (Total Travel Time)
  Time at court = 80 minutes - (10 + 10) minutes
  Time at court = 80 - 20 = 60 minutes.

Final Answer: He spent 60 minutes at the tennis court.