Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 5)
5.
A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?
120 m
240 m
300 m
None of these
Answer: Option
Explanation:

Speed = 54 x 5 m/sec = 15 m/sec.
18

Length of the train = (15 x 20)m = 300 m.

Let the length of the platform be x metres.

Then, x + 300 = 15
36

x + 300 = 540

x = 240 m.

Discussion:
276 comments Page 15 of 28.

Vicky said:   10 years ago
@Suraj we can also apply direct formula of speed on 15.

= 54*5/18 = 15.

Speed = Distance/Time.

15 = X/36-20.

X = 240.

Here 36-20 because both are in towards direction.

Srinivas said:   9 years ago
Actually, here it is asked for platform and train passed the platform. It doesn't matter train passed the man's distance. It's simple L = S*T but why you are including passed by man's time?

Appalaraju said:   9 years ago
d = s*t;

So d = 15 m.

l = x;

x/36-20 = 15.
x = 240.

R.sai said:   9 years ago
Another method we do that problem.

Train reach time-man standing time = 36-20 = 16.

Length = 15*16 = 240m.

PANASA HARISH KUMAR said:   9 years ago
Friends, I did like this to get an answer. I think it will help you.

Speed of train 54 km/hr 54*5/18 = 15 m/sec

Platform passed in 36 seconds

man stands on platform about 20 seconds
So, 36 - 20 = 16

Length of platform = Speed of train * time taken to pass(leftover seconds from man stood)
Distance = 15*16.
= 240.

Arzoo said:   9 years ago
Here, platform length is asked then only 36 sec would be considering I think. Because the man is standing on the platform then its passes time covered in 36 sec.

So please give me solution regarding this.

Lekh Raj ghallet said:   9 years ago
All of you have got answer rightly. According to my understanding, time spent by a train to cross a man is at the 20s. A man is standing at an extreme end of a train. Thus, a length of the train could be traded.

Soumya Saju said:   9 years ago
Friends, this method also can apply.

We know Time is taken by a train to cross a Standing man = (Length of the train) / (Speed of the train).

Thus, 20 = Length of the train/ (54 x 5/18).

So length of the train= 20 x 54 x 5/18 = 300 m.

Also, we know Time taken by a train to cross a Platform.

= (Length of the train+Length of the platform) / (Speed of the train).

I. E, 36= (300 + Length of the platform) / (54 x 5/18).

300+ So length of the platform = 36 x 54 x 5/18 = 540.

So, the length of the platform = 540 - 300 = 240 m.

Jyoti prakash giri said:   9 years ago
Let me put it straight 300 is the length of the train. Then in the problem, it should be treated as 300 + 300 + length of the platform.

It should take the tip as the entry and tail as exit and by that time it would have covered 600 m.

Cristianomahesh said:   9 years ago
Hii guys, I think.

Length = speed * time.

We have to find platform length so we have taken the man standing on platform time.

Therefore, length = 15 * 20.


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