A motorcyclist drives from place a to b with a uniform speed of 30 kilometre per hour and returns from place we to a with a uniform speed of 20 kilometre per hour find his average speed
Answers
A motorcyclist drives from place A to B with a uniform speed of 30 km/hr and returns from place B to A with a uniform speed of 20 kilometre per hour.
We have to find the average speed of the motorcyclist.
Let us assume that the distance covered by a motorcyclist is 'd' km.
Average speed is defined as the ratio of total distance covered with respect to total time taken.
Total distance covered by the motorcyclist is equal to the sum of distance covered from place A to B and place B to A.
Since, he is following the same pathway. So, the total distance covered by him is 2d (d+d).
Also,
Time = Distance/Speed
From place A to B time taken is:
t1 = d/30 hr
From place B to A time taken is:
t2 = d/20 hr
Total time taken by the motorcyclist = t1 + t2
= d/30 + d/20
= (2d + 3d)/60
= 5d/60
Average speed = (Total distance covered)/(Total time taken)
= 2d/(5d/60) = (2d × 60)/5d = 24 km/hr
Therefore, the average speed of the motorcyclist is 24 km/hr.