City A to city B, Andrew drove for 1hr at 50 mph and for 3 hours at 60 mph. What was the average speed for the whole trip?	Choose one:  A) 57  B) 57.5  C) 61  D) 61.5  E) 62.5
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 1hr at 50 mph and for 3 hours at 60 mph. What was the average speed for the whole trip?