Question

On a track 120km, a train travels the first 30km at a uniform speed of 30km/h How fast must the train travel the next 9km, so as to average 60km/h for entire trip?

Answer 1

Answer:

Explanation:

First time taken for 30km =30/30

T1=1hr

Because average speed=60km/hr

Total time=120/60=2hr

Now let time for rest 90km be t2 and speed be s2

Now t1+t2=2hr

t2=1hr

90/s2=1

S2=90km/hr