Question

A car travel at a speed of 20km/hr for 2 hrs and 60bkm/hr for next 2 hrs.what is the average speed?

Answer 1

1 st case
speed = 20 km/hr
time = 2 hr
therefore distance (d) = speed * time = 20*2 =40 km

2nd case
speed = 60km/hr
time = 2 hr
Therefore distance(D) = speed * time = 60*2 = 120 km
Now,
Total time =2 hr + 2 hr = 4hr
Total distance covered = d+ d = 40 + 120 = 160 km
Therefore av speed = distance / time = 160/4 = 40 km/hr