Question

A car travels 200km at a speed of 60km/h and return with a speed of 40km/h.calculate average speed for the entire journey .

Answer 1

Time=distance/speed
first 200km time =200/60
second 200km time=200/40
average speed=200÷200/60+200/40
=200÷20/6+20/4
=200/8.3
=24.096km/h(approx)

Answer 2

Time taken to go = 200/60=10/3hr
Time taken to return = 200/40=5hr
Total Distance = (200+200)km = 400km
Total time= (10/3 + 5/1)hr = 25/3 hr
Average speed = Total distance / Total time
=(400)/25/3
=(400)×3/25
=24km/h