A man travels 100 miles at 20 miles per hour, 60 miles at 30 miles per hour and 80 miles at 10 miles per hour, what is his average rate for the three trips?

Correct Answer: 16 miles per hr
Time travelled at 20 miles//hr = 100/20 = 5 hrs Time travelled at 30 miles//hr = 60/30 = 2 hrs Time travelled at 10 miles//hr = 80/10 = 8 hrs Total time travelled = 5 + 2 + 8 = 15 hrs Total travelled = 100 + 60 + 80 = 240 miles Average rate = 240 / 15 = 16 miles per hour