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 22 of 28.
Shakya said:
1 decade ago
You can take this question as:-
A train can pass a station platform in 36 seconds and it can pass a man standing somewhere not only on platform (this statement shows the point is stationary) in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?
speed=15 m/s
train length=15*20;
train length + platform length= 15*36=540;
platform length = 540 - train length;
platform length = 240 m (answer)
A train can pass a station platform in 36 seconds and it can pass a man standing somewhere not only on platform (this statement shows the point is stationary) in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?
speed=15 m/s
train length=15*20;
train length + platform length= 15*36=540;
platform length = 540 - train length;
platform length = 240 m (answer)
Shro said:
1 decade ago
@Abhishek here we are supposed to find the length of the platform.
once we find the speed of train that is 15msec.
length or distance=speed * time
so length of train = speed of train is 15m/s multiplied by the train taking time to cross the man's position in 20secs.
so= 15 * 20
If u calculate in this way ,then as per the mathematics , u will come to know where the man is standing....
In such cases Solve as per the formulas.
Hope u got it :)
once we find the speed of train that is 15msec.
length or distance=speed * time
so length of train = speed of train is 15m/s multiplied by the train taking time to cross the man's position in 20secs.
so= 15 * 20
If u calculate in this way ,then as per the mathematics , u will come to know where the man is standing....
In such cases Solve as per the formulas.
Hope u got it :)
Abhishek said:
1 decade ago
But we don't know where man is standing on the platform. Do we ?
And if we don't know that then how do we supposed to do 15x20= 300 ?
Can anyone tell me that. ?
And if we don't know that then how do we supposed to do 15x20= 300 ?
Can anyone tell me that. ?
Shro said:
1 decade ago
@ Rahul Nicely explained ...thank you :)
Rajasekhar sarvepalli said:
1 decade ago
Since the train is moving toward the man you can do 36-20 seconds = 16 seconds.
Logically if u think whenever u stand on a platform and train is coming towards you the the speed of a man becomes lesser than the speed of a train.
there for distance = speed x time = (54 x 1000 meters/ 3600 seconds).x 16 sec
= 15 x 16
= 240 meters
Logically if u think whenever u stand on a platform and train is coming towards you the the speed of a man becomes lesser than the speed of a train.
there for distance = speed x time = (54 x 1000 meters/ 3600 seconds).x 16 sec
= 15 x 16
= 240 meters
Sujay Kumar Sardar said:
1 decade ago
@Ranjita
No Ranjita. 540m is the total distance(length) covered by train i.e its own
Length plus length of the platform= 540m
Though we know length of the train i.e 300m
Therefore length of the platform is (540m-300m)= 240m.
No Ranjita. 540m is the total distance(length) covered by train i.e its own
Length plus length of the platform= 540m
Though we know length of the train i.e 300m
Therefore length of the platform is (540m-300m)= 240m.
Mohd Imran said:
1 decade ago
Hi friends,
length of the platform = speed*time
so,speed =54km\hr
1km=1000
1hr=60*60=3600secs
so,km/hr=1000/3600=5/18
km/hr=0.2777
so,speed =54*0.277=15
and time=36-20=16.
so length of the platform=speed*time=15*16
length of the speed =240m.
so the answer is(b)
length of the platform = speed*time
so,speed =54km\hr
1km=1000
1hr=60*60=3600secs
so,km/hr=1000/3600=5/18
km/hr=0.2777
so,speed =54*0.277=15
and time=36-20=16.
so length of the platform=speed*time=15*16
length of the speed =240m.
so the answer is(b)
Ranjitha said:
1 decade ago
Actually the answer can b 540.
15*36=540.
15*36=540.
Rahul said:
1 decade ago
Please tell me the reason why we can not calculate lenght of train through 15*36=540 can we calculate lenght of train like this if nt thn tell me reason.
Baskar.R said:
1 decade ago
Speed = 54x5m/sec = 15 m/sec
15*36=540
man standing= 15*20=300
ans= platform length=540-200
ans= 240
15*36=540
man standing= 15*20=300
ans= platform length=540-200
ans= 240
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