Aptitude - Time and Distance - Discussion

(Relative speed/maximum speed) * 60min.

There's a formula for this type of ques:

Speed of bus (excluding stoppage) - Speed of bus (including stoppage) * time/ speed of bus (excluding stoppage).

If you put values in this formula:
Speed of bus without stoppages= 54-45 = 9km/hr,
Time = 1 hr.
So, distance without stoppages = 9 *1= 9 km.

[(54-45) / 54] * 60 = 10.

We have taken the difference of speeds of excl and incl stoppages because we want distance without stoppages. We have taken 54 as denominator because the bus has stopped. We have multiplied it by 60 because the options are in minutes and we were getting answer in hours. If we had options in hours, so we won't have needed to multiply 60.

Can't we consider like taking the ratio of speed and time since distant is constant, time is inversely proportional to speed?

From which we can get the ratio of stoppage to total travel time. Please explain to me.

(Without stoppage-with stoppage)/Without stoppage.

(54-45) /45.
(9/60) *60.
10 min.

Let's suppose,

Excluding stoppages speed (s1) and including stoppages speed (s2)
then;

The stoppage minutes per hour = (difference b/w the speed(s1~s2))/(Excluding stoppages *60 minute speed (s1)).

Thanks for the answer @Jaya.

See I will reframe the question to understand it in a better way.. Bus has started from point A. there are stops in between till point B so its speed is less i.e. 45km/hr. Now after this point there are no stops so it increases its speed to 54km/hr to reach point C. We have to find the time lapse of distance covered between these two speeds. lets find the distance 1st.
s=d/t.
let's say time taken be 1hr. so acc to this distance covered till point B is 45km
n from B to C is 54km
So, the distance gap is of 9km.

Now the time lapse for this distance we have to find. the extra distance from B to C is covered with speed of 54km/hr.
Thus, t= 9/ 54 is 1/6 hr.
So 1/6hr * 60 = 10 mins.

Simply, the solution is;

60min --> 54km
x min --> 45

>>x=50;

This means with stoppages it is taking 50 min to reach 45km.
but now without stoppage it is taking 60 min so with stoppage it is taking extra 10 min.

Let the distance be 270 km.
During normal speed, i.e 54 km/hr. The time taken =5hrs.
And with the average speed of 45 km/hr, the time taken is 6 hrs, i.e 60 minutes more.
My doubt is that these 60 minutes must have been spending in the interval of 5 hrs, i.e 12 minutes per hour.
Why can't the answer be 12 minutes?

Let 54 km and 45 km is a distance that travelled by bus in *1hour*.

45 km distances travelled by car in 1 hour due to the stoppage.
If it travels without a stoppage, it would cover in a 45km/ 54kmph = 5/6h.
5*60/6 = 50 min,
60-50 = 10 minutes.