Aptitude - Problems on Trains - Discussion

Speed=54*(5/18)=15m/s.

Now time = 36-20=16.

Now distance(i.e length)=speed*time
=15*16
=240m/s.

First we are calculate the length of train compared with a man standing on the platform.

= (15*20) m.

=300m.

Second we are calculate the length of train compared with they passes a station platform.

= (15*36) m.

=540m.

We wanted to the length of platform X.

So, the length of platform X and the length of train compared with a man standing on the platform equal to the length of the train compared with they passes a station platform.

X+300m=540m.

X= (540-300) m.

=240m.

We were got the length of platform 240m.

Distance=Time*Speed.

* 54 x 5/18 = 15

* 15 x 20(given) = 300

* x+300/36=15
=240m

OR

* Distance = speed*time
* Distance = (54*5/18)*(36-20)
= 15*16
= 240
Speed , Time is given to us. We have to only apply the formula in proper way.

Time taken for reach the platform=36sec.

Time taken for reach a man= 16sec.

Speed (S) = (54*5) /18=15.

Distance between=36-20=16.

Then the distance=16*15.

=240.

Why x and 300m are added?

In simple process,

Bs-------------------m------------Be

A--------20S---------B------16S---C

l---------------36s---------------l

If man was reference point then T.P=36-20=16s.
We know length=speed*time.
Then lenth of train=(54*5/18)*16=15m/s.*16s.=240m.

Answer=240m.

Speed of the train=54km/hr.

Speed=54*5/18=15.

Train passes a station platform:Length=speed*time.

=15*36=540.

Train passes the man standing on the platform:Length=speed*time.

=15*20=300.

Length of the platform=540-300=240m.

Train crossing station platform in 36 sec with speed of 54km/hr. Question asked what is the length of platform?

54 x 1000 /3600 = 15m/sec train travel distance.

So for 36 sec train is crossing the platform.

Total length of the platform is 36 x 15 = 540mts.

If question asked what is the length of train then we have to calculate 20 sec X 15 m /sec = 300 mts.

If asked what is the balance length of platform from man standing place, then (36-20= 16) 16 x 15 =240mts.

I hope my view is correct.

The train pass the man 20sec, and the train pass a station 36sec.

So,36-20=16sec

Then we know that speed of the train of the train is 54km/hr.
=15m/sec

Therefore, 16*15=240m. Answer.

Train passes in 36 secs, man standing in 20 secs.

Therefor, 36-20= 16 secs.

Now, speed = 54 km/hr.

= {54 X 5/18} = 15 m/sec.

Here, length = speed X time

= 15 X 16
= 240 m. ans