Answer:
Average speed = 53.33 km/h
Explanation:
Below is the calculation for the average speed:
Given the average speed of for first 40 km = 80km/h
Time taken to cover the first 40 km = Total Distance / average speed
Time taken to cover the first 40 km = 40 / 80 = 0.5 hours
Given the average speed of for next 40 km = 40km/h
Time taken to cover the next 40 km = Total Distance / average speed
Time taken to cover the next 40 km = 40 / 40 = 1 hours
Now the average speed of the tuck to cover total distance:
Average speed = Total distance / Total time
Average speed = (40 + 40) / (0.5 + 1)
Average speed = 53.33 km/h