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?  Choose the correct choice from the following answers.
A) 56	B) 57.5	C) 58.9	D) 61.4	E) 62

Rationale: 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 b
Answer: B