Aptitude - Time and Distance - Discussion

S1 = 54kmph
S2 = 45kmph
T=?.

D = S2-S1=> 54 - 45 = 9km.

# Due to stoppages it travels 9km less than its usual distance,
Time = Distance/Speed.
= 9/54 (S2 speed is taken to calculate the stopping time)
=1/6hr.

# To convert hr to min "*" by 60=>(1/6)*60 = 10min.
Therefore it stops 10min every hour in stoppages
Time = speed/distance.

If he travels for 10 km.

54 kmph means 54x10= 540.
45 kmph means 45x10= 450.

Difference of distance 540-450=90km,
Difference of speed 54-45=9.
.Distance=speed x time.
90 = 9xtime,
time = 10.

Its very simple,

Firstly,
54 - 45 =9 due to stoppages,it covers 9km less.
Time taken to cover 9km = (9/54 x 60) =10mins. And in "1 min there are 60 seconds".

I can't understand. Can anybody explain me?

Due to stoppages, it covers 9 km less.

Time taken to cover 9 km = 9 x 60 min = 10 min.

Excluding the stoppages, it is 54kmph. Here the question is about the time taken at every stop, which should be calculated using the speed taken when including the stops, that is 45 kmph. Why is it taken as 54?

Please explain me.

(Initial - final/initial) hours = covert to minute and get the answer.

Speed is 54 km/hr, here clarity is speed is never reduced.

So in one hour, it covers 54 km without stopping, now since it has stopped it covered only 45 km at speed of 54 km/hr. had it not stopped it would have covered 54 kms, but it stopped hence it covered only 45 km.
Distance not covered is 54 - 45 = 9kms.
Now the time it would have taken to cover 9kms is (time = distance/speed)
Time reqd to cover 9 km @ 54km/hr = 9/54 = 1/6 hours i.e 10 minutes.

@All.

Consider the distance is only 54 kms. At 54 kmph it will take only 1 hr.
But since due to stoppages it takes 10 minutes extra (the time of stoppages).
So, shouldn't we get 45 kmph if we divide 54 km the distance by 1 hr 10 minutes (70 minutes)? We don't get that, of course. The bus runs at 54 and with the stoppage, rit reaches 45 km. 9 km is remaining. The average speed with stoppages was 45kmph. the remaining distance of 9 km has to be completed by that average speed as there are no more stoppages to get the correct time taken by the bus and not by 54kmph.

So, it will work out to be 12 minutes, not 10 minutes.

Thanks for explaining @Anoo.