posted by Courtney .
A truck driver traveled at an average speed of 55 miles per hour on a 200 mile trip to pick up a load of freight. On the return trip(with the truck fully loaded), the average speed was 40miles per hour. What was the average speed for the round trip?
Average speed = total distance traveled/total time taken
time for first leg of trip =200/55 hrs
time for second leg of trip = 200/40 hours
so average speed = 400/(200/55 + 200/40)