A motorcyclist travels 50 miles with an average speed of 40 mph and then another 20 miles with an average speed of 55 mph. What was the average speed of the cyclist over the entire 70 miles?
Time must be considered in 'average speed' questions
50 m / 40 m/hr = time during 50 mile ride
20 m / 55 m/hr = time during 20 mile ride
total ride = 70 miles
total ride / total time = average
70 m / ( 50/40 + 20/55) = 43.4 m/hr avg