a truck driver traveled at an average speed of 48 miles per hour on a 100-mile trip to pick up a load of freight. On the return trip with the truck fully loaded,the average speed was 40 miles per hour. Find the average speed for the round trip.
math - Reiny, Sunday, March 7, 2010 at 10:50pm
time for first trip = 100/48 hours = 25/12 hrs
time for return trip = 100/40 = 5/2 hours
total time = 5/2 + 25/12 hours = 55/12 hrs
avg speed = total distance / total time
= 200/(55/12) = 43.64 mph