Problem 1

A car traveled 100 miles from A to B at 60 mph, and returns at 40 mph. What is the average speed for the round trip?

[Problem submitted by Henry Cataldo, LACC Professor Emeritus of Mathematics.]

Solution for Problem 1:

Time from A to B = 100/60 = 5/3 h.

Time from B to A = 100/40 = 5/2 h.

Total time = 5/3 + 5/2 = 25/6 h.

Average speed = 200/(25/6) = 48 mph.