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?

43.48 mph

Explanation:

We are given;

First instance;

Distance = 50 miles Speed = 40 mph

Second instance;

Distance = 20 miles Speed = 55 mph

We are required to determine the average speed for the entire journey.

Average speed = Total distance : total time We need to calculate time;

Time = Distance : speed

First instance

Time = 50 miles : 40 mph

= 1.25 hours

Second instance;

Time = 20 miles : 55 mph

= 0.36 hours

Therefore;

Total distance = 70 miles

Total time = 1.25 hrs + 0.36 hr

= 1.61 hrs

Thus;

Average speed = 70 miles : 1.61 hrs

= 43.478 miles per hour

= 43.48 mph