What is the average speed of the round trip?

Question

Suppose you run 5 miles from your house to a friend’s house at a speed of 4 miles per hour. When the time comes to return home, you are tired and walk the same 5 miles home at 2 miles per hour.

Answer 1

Distance = (Rate)(Time). So, Time = Distance / Rate

Time going to the friend's house = 5/4 = 1.25 hours

Time coming home = 5/2 = 2.5 hours

Average speed of round trip = (Total distance) / (Total time) = 10/3.75 = 2 2/3 mph