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?
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 4 of 28.
Raj said:
9 years ago
Distance = time * speed.
Sspeed of train = 54 * 5/18 = 15 m/s.
Time taken by train to cross man= 20s,
Therefore distance/length of train = 20 * 15 = 300m,
Time taken to cross platform= 36s.
Length of train + length of platform = time * speed.
Which implies,
Length of platform = (36 * 15) - length of train.
Length of platform = 540 - 300,
Length of platform = 240m.
Sspeed of train = 54 * 5/18 = 15 m/s.
Time taken by train to cross man= 20s,
Therefore distance/length of train = 20 * 15 = 300m,
Time taken to cross platform= 36s.
Length of train + length of platform = time * speed.
Which implies,
Length of platform = (36 * 15) - length of train.
Length of platform = 540 - 300,
Length of platform = 240m.
Dheeraj said:
1 decade ago
Can some tell me which formula we are applying for for
x+300
-----=15
36
I understood that once we multiply 15 and 36 we will get 540......
But, why we are multiplying them......?
Is it because of distance = speed * Time.....???
Explain me please???
x+300
-----=15
36
I understood that once we multiply 15 and 36 we will get 540......
But, why we are multiplying them......?
Is it because of distance = speed * Time.....???
Explain me please???
JEEVAN said:
9 years ago
The length of the train = the time * speed
= 15 * 20 seconds taken by it to pass the man as the man is standing at one point.
= 300m
The length of the platform = remaining time * speed.
= (36 - 20) * 15.
= 16 * 15.
= 240.
= 15 * 20 seconds taken by it to pass the man as the man is standing at one point.
= 300m
The length of the platform = remaining time * speed.
= (36 - 20) * 15.
= 16 * 15.
= 240.
Ravi.Managuli said:
1 decade ago
Speed = (54 x 5/18) m/sec = 15 m/sec.
Length of the train = (15 x 20)m = 300 m.
Let the length of the platform be x metres.
Then x+300 = 36*15.
(Because: Time taken by a train of length l metres.
To pass a stationary object of length b metres.
Is the time taken by the train to cover (l + b)metres.)
Then x + 300 = 540.
x = 240 m.
Length of the train = (15 x 20)m = 300 m.
Let the length of the platform be x metres.
Then x+300 = 36*15.
(Because: Time taken by a train of length l metres.
To pass a stationary object of length b metres.
Is the time taken by the train to cover (l + b)metres.)
Then x + 300 = 540.
x = 240 m.
Sabarish said:
1 decade ago
@saikiran
here speed of the train given as in km/hr . so first we convert it into m/sec [i.e 54km/hr*(5/18)=15m/sec]. 5/18 is used to convert train speed into m/sec.
Then if you want length of the train means,you;ll use below formula:
Length of the Train=Speed*time
It is general formula in train based questions..
Have a nice day for you..
here speed of the train given as in km/hr . so first we convert it into m/sec [i.e 54km/hr*(5/18)=15m/sec]. 5/18 is used to convert train speed into m/sec.
Then if you want length of the train means,you;ll use below formula:
Length of the Train=Speed*time
It is general formula in train based questions..
Have a nice day for you..
Premchandra saka said:
1 decade ago
First calculate length of both platform and train = (Train cross the platform)*Train speed in second = 36*(54*5/18) = 540 meter.
Then Train length = Speed in meter per second*Cross the man in second.
= 15 m/sec*20 sec = 300 meter.
Now, Platform length = Both platform and train length - Train length.
= 540 meter-300 meter.
= 240 meter.
Then Train length = Speed in meter per second*Cross the man in second.
= 15 m/sec*20 sec = 300 meter.
Now, Platform length = Both platform and train length - Train length.
= 540 meter-300 meter.
= 240 meter.
Ashwini Dharam said:
9 years ago
Hi, Friends,
Here given is that train takes 36 sec to cover a distance which is the length of the platform. Because here clearly given that. The train which is having speed 54km/hr takes time 36 sec to cover distance i.e the length of the platform. So I think there is no need to take into consideration the length of the train.
Here given is that train takes 36 sec to cover a distance which is the length of the platform. Because here clearly given that. The train which is having speed 54km/hr takes time 36 sec to cover distance i.e the length of the platform. So I think there is no need to take into consideration the length of the train.
Dharmendra (dj) said:
8 years ago
As we know,
A train passes a station platform in 36 seconds and man standing on the platform in 20 second.
We have speed of train is 15m/s,
So,
We know a man standing and train crossing platform
36-20=16 sec
Now we have actual time
Then distance= Time x speed
X. = 16x15 m/s
X= 240 m
Distance=240m.
A train passes a station platform in 36 seconds and man standing on the platform in 20 second.
We have speed of train is 15m/s,
So,
We know a man standing and train crossing platform
36-20=16 sec
Now we have actual time
Then distance= Time x speed
X. = 16x15 m/s
X= 240 m
Distance=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.
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.
Gaurav said:
7 years ago
A simple one trick:
Here train crosses a platform and a man standing on a platform in the same direction i.e. 36 - 20 = 16 sec is relative timing.
And speed of the train is 54 km/hr i.e. 15 m/sec
Now we have speed and time then apply formula;
The solution is length= 15 x 16 = 240 m.
That's all.
Thank you.
Here train crosses a platform and a man standing on a platform in the same direction i.e. 36 - 20 = 16 sec is relative timing.
And speed of the train is 54 km/hr i.e. 15 m/sec
Now we have speed and time then apply formula;
The solution is length= 15 x 16 = 240 m.
That's all.
Thank you.
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