Lokman bikes from her home to her office at a constant speed of 20 km/h, and she bikes back home at a constant speed of 40 km/h. What is closest to the average speed of her bike over time in km/h?
Expain all your steps, in detail.
time for commute to work = distance / rate = d/20
time for bike ride home = d/40
total distance = 2d
distance/total time = rate
2d/(d/20+d/40) = 2d/(2d/40 + d/40) = 2d/(3d/40) = 2 d * 40/3d = 80/3 = 80/3 km/hr = 26.67 km/hr average