Question

A truck with a heavy load drove from Boston to New York at 45 mph. After unloading, it returned from New York to Boston at a speed of 65 mph. What was its average speed for the whole trip?

Answer 1

Average speed: 585/11 or 53 2/11

Explanation:

Let distance from New York to Boston, and vice-versa, be D

Then, time taken to travel from Boston to New York is: D/45

Also, time taken to travel from New York to Boston is: D/65

Total time taken for entire trip: D/45+D/65

Average speed: total distance/total time

Average speed: 2D/22D/585

Average speed: 53 2/11 or 585/11 mph