Question

a cyclist covers a distance of 15 km at 5 km/hr and next 25 km at km/hr.if he returns the whole distance with a speed of 6 km/ hr find the difference in time taken in forward and reverse journey​

Answer 1

time taken by cyclist to cover first distance 15km distance at 5km/hr = (D/S)

= (15km/5 km)hr

=3 hr.

time taken by cyclist to cover second distance 25 km at 25km/hr=(D/S)

=(25km/1km)hr

=25 hr.

So, total distance cover by the cyclist=(15 +25)km= 40 km.

And, total time need to cover the given distance=(3+25)hr= 28 hr.

Now,

the cyclist returns from the whole distance at 6km/hr,

So, time taken by cyclist to return from the covering distance =(D/S)

=(40km/6km)hr

= 20/3 hr

Thus, covering time=28hr,

And, returning time = 20/3 hr

So, difference in time in forward and reverse journey= (28/1 - 20/3)hr

=((84-20)/3) hr

= (64/3)hr

=21.3333 hr

=21hr 18 min .Ans. (1hr =60min)