Question

Bikash travels half of his journey by train at a speed of 120 km/h and rest half by car at 80 km/h. what is the average speed?

Answer 1

Let the distance be 2d
Let the time be t.
Case1:
Speed=120
Time=t¹=distance/speed¹
T¹=d/120
Case2:
Speed=80
Time=t²=distance/speed²
T²=d/80
Now,
Total distance=2d
Total time=t¹+t²=d/120+d/80=(80d+120d)/(120×80)
=200d/9600
=D/48
Now,
Average Speed=total distance/total time
=2d/d/48
=2d×48/d
=96km/h
(ÆÑẞWĒR)