city A to city B, Andrew drove for 1 hour at 50 mph and for 3 hours at 60 mph. What was the average speed for the whole trip?  Answers
A) 57  B) 57.5  C) 56  D) 59  E) 60
The total distance is 1×50+3×60=2301×50+3×60=230. And the total time is 4 hours. Hence,   Average Speed=(Total DistanceTotal Time)=2304=57.5   57.5
<result>B</result>
city A to city B, Andrew drove for 1 hour at 50 mph and for 3 hours at 60 mph. What was the average speed for the whole trip?