Answer: Average speed = 50.0 miles per hour
Explanation:
Time = distance/speed
The truck driver traveled at an average speed of 58 miles per hour on a 200-mile trip to pick up a load of freight.
Time taken to travel this distance is
200/58 = 3.44 hours
On the return trip (with the truck fully loaded), the average speed was 38 miles per hour. Time taken to travel this distance is
200/38 = 5.26 hours
Total distance travelled on the round trip is 200 + 200 = 400 miles
Total time spent = 3.44 + 5.26 = 8.7 hours.
Average speed = total distance/total time taken
Average speed = 400/8.7 = 50.0 miles per hour