Aptitude - Time and Distance - Discussion

How it came?

Right @Jaya.

Why we do not consider 45? explain.

@Bharathi.

The main scenario is that, in one condition, the time taken by the bus for the stoppage in an hour, in another condition in that time the bus travelled some extra distance.

So, we have to calculate in how much time it travels the total extra distance i.e. 9 km and that is the time the bus spent on stoppages.

That's why we didn't consider 45.

The average speed (including stoppage) is 45 km/hr.
Distance = (rate)(time).
So, in ONE hour, the distance traveled = (45)(1) = 45 km.

The average speed (excluding stoppage) is 54 km/hr.
At this speed, HOW long will it take the bus travel 45 km?
time = distance/rate.
So, time = 45/54.
= 5/6 hours,
= 50 minutes.

At a speed of 54 km/hr, the bus can travel 45 km every 50 minutes.
So, it must be motionless for the other 10 minutes.

The distance between A and B is 999km.The express train travels place A at 6 a.m. and runs at the speed of 55.5 kmph. The train stops on the way for 1 hour 20 minute.The train reaches B at?

Please solve this question.

There is another easier method.

54 km is traveled in 1 hr
1 km------------- 1/54 hr
45 km---------- 1/54*45= 5/6 hrs.

Now, if we subtract the times, i.e 1 - 5/6 = 1/6 hr (we are subtracting this because 45 km should have been traveled in 5/6 hrs and not 1 hr. Hence, the time taken is more so subtracting, we get the no. of minutes the bus stopped).

converting to minutes 1/6 * 60 = 10 min.

Due to stoppages, the bus lags =(54-45)Kmph=9Kmph in speed.
So, time taken at each stoppages= Speed /original speed.
=9/54 hrs,
=9*60/54mins,
=540/54mins,
=10mins.

Consider A and B two bus,

A with stoppages km/hr - 45
B without stoppage km/hr - 54

1 hour travel.
B far away from A.
that distance is 9 km.

Just think 9 km A don't stop in anywhere there speed is increased. Because A's is the Avg speed 45 km/hr.

Here we can't find the stoppage from A's speed
Go next option B,
from B the bus,
Easy to find out the time taken from 9 min travel that 9 min travel is A's stoppage time

So,
distance = time * speed,
54 km = 1 hour * 54 km/hrs,
if 1 km = time ? * 54km/hrs,
9 = t* 54,
1/6 = t (in hours),

In min,
1/6*60 =10min,

Can anyone clearly explain why we had taken 9/54 instead of 9/45?