Joe Cool drives to see his girlfriend who attends another college

Question

A) The 163 km trip takes 2.0 h. What was the average speed for the trip?

B) The return trip over the same route takes 3.0 h because of heavy traffic. What is the average speed for the return trip?

C) What is the average speed for the entire trip?

Answer 1

Average speed is (total distance)/(elapsed time) = (163 km)/(2.0 hr) = 81.5 km/hr but because there are only 2 sig figs in the time (2.0 hrs), I would round the final answer to 2 sig figs and state the average speed was 82 km/hr

For the return trip 163/3 = 54 km/hr.

For the total trip: (163 + 163)/(2 + 3) = 326/5 = 65 km/hr