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 24 of 28.
Mansi said:
5 years ago
As the man is not moving and he can be ignored as a little particle because he has not such a big length (his standing distance) as a pillar.
So if we take the time of the train passes the man, we can get the exactly length of the train.
So there, the length of the train= (15*20).
If the man would have moving, there we can't take the same length.
We are not taking the time of the platform because it has a big length which can't be ignored.
So if we take the time of the train passes the man, we can get the exactly length of the train.
So there, the length of the train= (15*20).
If the man would have moving, there we can't take the same length.
We are not taking the time of the platform because it has a big length which can't be ignored.
VISHESH said:
5 years ago
Time taken by train to pass a station platform = 36 seconds.
Time taken by train to pass a man on platform = 20 seconds.
Speed of train = 54 km/hr.
= ( 54 * 5/18,
= 3 * 5,
= 15 m/s.
length of train = 15 *20.
= 300 m.
Let the length of train be x.
Then;
300 + x /36 = 15.
300 + x = 15*36,
x= 540 -300,
x =260.
So, length of the platform is 240m.
Time taken by train to pass a man on platform = 20 seconds.
Speed of train = 54 km/hr.
= ( 54 * 5/18,
= 3 * 5,
= 15 m/s.
length of train = 15 *20.
= 300 m.
Let the length of train be x.
Then;
300 + x /36 = 15.
300 + x = 15*36,
x= 540 -300,
x =260.
So, length of the platform is 240m.
Tayek said:
5 years ago
Thanks @Satheesh.
Avinash Kapu said:
5 years ago
In this problem, it is considered that the man is standing at the extreme end. That's the reason length of the train is calculated as 15*20. What if the man is standing in the middle of the platform.
Jackiep said:
5 years ago
Time taken to pass a station = 36s.
Time taken to pass a man = 20s.
Difference=16s.
We have,
Distance = Speed X Time.
= 15 X 16.
= 240m.
Time taken to pass a man = 20s.
Difference=16s.
We have,
Distance = Speed X Time.
= 15 X 16.
= 240m.
(1)
Manikandan said:
5 years ago
From the given data, we can consider the only man as a reference point to find the length of train. So let us consider man is standing at the beginning, so 15*20 will be enough to find the length of the train, Am I right?
Udaya said:
5 years ago
Shortcut method:-
Train + Platform = 36 sec.
Train = 20sec.
Extra it takes 16 sec to travel platform.
Covert kmph to m/s because we need answer in m/ s.
54kmph*5/18 = 15m/s.
15* 20 = 300m train length.
It takes 20 sec ---> 300m
16sec ---> ?????
Less by more concept 16/20 *300 = 240 m.
Train + Platform = 36 sec.
Train = 20sec.
Extra it takes 16 sec to travel platform.
Covert kmph to m/s because we need answer in m/ s.
54kmph*5/18 = 15m/s.
15* 20 = 300m train length.
It takes 20 sec ---> 300m
16sec ---> ?????
Less by more concept 16/20 *300 = 240 m.
(2)
Aniket Masalkhamb said:
4 years ago
You can multiply 15 * 36 which gives you 540m then x be the length of the platform therefore as speed = distance upon time 540 +x/20 = 15.
x = 240m.
x = 240m.
Jai said:
4 years ago
t1-t2 = 36 - 26 = 16.
We know 54 x 5/18=15,
So putting in formula s=d/t.
15 = d/16, where d is taken as length here;
d = 15 * 16,
= 240.
We know 54 x 5/18=15,
So putting in formula s=d/t.
15 = d/16, where d is taken as length here;
d = 15 * 16,
= 240.
Keerthi said:
4 years ago
Why we, not multiple 15 * 36 instead we multiple 15 * 20? Please explain.
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