on a trip covering 400 km , a bicyclist travels the first 100 km at 20 km per hour and the remainder of the distance at 15 km per hour . what is the average speed , in km per hour , for the entire trip ?
time 1 = 100 / 20 = 5 hours time 2 = 300 / 15 = 20 hours total time = 25 hours average speed = 400 / 25 = 16 km / hr the answer is b .
speed(400, add(divide(100, 20), divide(subtract(400, 100), 15)))