Winson traveled the entire 60 miles trip. If he did the first 10 miles of at a constant rate 20 miles per hour and the remaining trip of at a constant rate 48 miles per hour, what is the his average speed, in miles per hour?
Choose the correct answer
A) 20mph  B) 24mph  C) 30mph  D) 32mph  E) 40mph
Average speed=sum of distance/sum of time. If he travelled the first 10 miles at 20 miles/hr, it would take 0.5 hr. For the remaining trip, if he went at 48 miles/1hr, it would take 1 hour. Then, the average speed is 60miles/(0.5+1)hrs=40miles/1hr.   Therefore, the answer is 40mph.
<result>E</result>
Winson traveled the entire 60 miles trip. If he did the first 10 miles of at a constant rate 20 miles per hour and the remaining trip of at a constant rate 48 miles per hour, what is the his average speed, in miles per hour?