Question

a car moves with a speed of 10 kilometre per hour for half an hour and 20 kilometre per hour for 1 hour for one hour and 50 kilometre per hour for 2 hours calculate the average speed of the car

Answer 1

total distance covered = 5 + 20 + 100 = 125 km = 125000 m
total time taken = 0.5 + 1 + 2 = 3.5 hr = 210 minutes = 12600 secs

av speed = distance / time = 125000/12600 = 9.9 m/sec