Question

A motorist travels 320km at 80km/h and then 320km at 100km/h. What is the average speed of the motorist the entire journey?

Answer 1

Step-by-step explanation:

rate * time = distance

distance / rate = time

320 km / 80 km/hr = 4 hr

and 320 km / 100 km/hr = 3.2 hr

total time = 4 + 3.2 = 7.2 hr

total distance = 320 + 320 = 640 km

average rate = total distance / total time = 640 km / 7.2 hr = 88.9 km/hr