A runner runs 3.0 km, in a straight line, in 9.0 min and then takes 25 min to walk back to the starting point. (The running and walking is in a straight line.)
(a) What is the runner's average velocity for the first 9 min? km/h
(b) What is the average velocity for the time spent walking? km/h
(c) What is the average velocity for the whole trip? km/h
(d) What is the average speed for the whole trip? km/h