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 3 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)
Amit Kr. Soni said:
2 decades ago
Finally I solve question in my own language.
Time to cross the man = 20 sec
Speed of train = 54 km/hr, = 54*5/18, 15 m/sec .......... (1)
Now length of train = 20*15 (fm distns = spd * time) = 300 mtr
Now let length (ditns) of pltfrm = x mtr.
Totl lenth (distns) = 300 + x
Spd = 15 m/sec ........from eqan(1)
According to question,
300 + x/15 = 36, [b'coz trn complet d totl distns in 36 sec]
So x = 540 - 300 = 240 Answer
Time to cross the man = 20 sec
Speed of train = 54 km/hr, = 54*5/18, 15 m/sec .......... (1)
Now length of train = 20*15 (fm distns = spd * time) = 300 mtr
Now let length (ditns) of pltfrm = x mtr.
Totl lenth (distns) = 300 + x
Spd = 15 m/sec ........from eqan(1)
According to question,
300 + x/15 = 36, [b'coz trn complet d totl distns in 36 sec]
So x = 540 - 300 = 240 Answer
Rkk said:
1 decade ago
Sorry friends the question was asked about the total length of platform.
So the total length is,
Speed = 54*(5/18) m/sec.
Length between man and starting point of platform = ( 15*20 ) = 300 m.
x be the length between man and end point of platform and train cross the total length in 36 sec.
So,
300 + x is the total length of platform.
( 300 + x )/36 = 15.
= 240.
Total length = 300 + 240 = 540.
So the total length is,
Speed = 54*(5/18) m/sec.
Length between man and starting point of platform = ( 15*20 ) = 300 m.
x be the length between man and end point of platform and train cross the total length in 36 sec.
So,
300 + x is the total length of platform.
( 300 + x )/36 = 15.
= 240.
Total length = 300 + 240 = 540.
Arockiaraj said:
10 months ago
Train passes 36 sec.
Man standing 20 sec.
Train speed = 54 km/h.
platform length = ?
Train length = (54*5/18) * 36.
= 30/2 * 36.
= 30 * 18.
Train length = 540.
Platform length = (54*5/18) * 20.
= 30/2 * 20.
= 30 * 10.
= 300.
Platform length = 540 - 300.
= 240=> Ans.
Man standing 20 sec.
Train speed = 54 km/h.
platform length = ?
Train length = (54*5/18) * 36.
= 30/2 * 36.
= 30 * 18.
Train length = 540.
Platform length = (54*5/18) * 20.
= 30/2 * 20.
= 30 * 10.
= 300.
Platform length = 540 - 300.
= 240=> Ans.
(32)
Najma said:
1 decade ago
I think it should be the logic, initially total length of the train couldn't on platform. It takes 20 sec (reference point where the man stand) to be on platform completely. From that reference point only the train completely travels on platform. That why we are subtracting the time 36-20=16sec it is the time train completely on platform.
Now calculate length = (54*5/18) *16 sec = 240 sec.
Friends. Am I correct?
Now calculate length = (54*5/18) *16 sec = 240 sec.
Friends. Am I correct?
Rahul said:
2 decades ago
Length of the train is always calculated considering the train passes through a REFERENCE POINT. Here platform cannot be a REFERENCE POINT as it has some length. Thus man is taken as REFERENCE POINT to calculate the length of the train. Here train takes 20 seconds to cross REFERENCE POINT (man). Thus the train speed is multiplied by 20 seconds (15*20) to calculate the length of the train.
Justin Gj said:
2 years ago
Since the options given are in meters, we must first convert given into m/s.
Speed of train =54km/hr = 54*5/18 = 15m/s.
Then find the length of the train using D = S * T eqn in the case of a man
Length of train =15 m/s *20 secs =300m.
Then while passing the platform, Total length =(train length +platform length) = 15m/s * 36 secs =540m.
Therefore platform length = 540m - 300m = 240m.
Speed of train =54km/hr = 54*5/18 = 15m/s.
Then find the length of the train using D = S * T eqn in the case of a man
Length of train =15 m/s *20 secs =300m.
Then while passing the platform, Total length =(train length +platform length) = 15m/s * 36 secs =540m.
Therefore platform length = 540m - 300m = 240m.
(41)
Nusrath Kamal said:
1 decade ago
Why you all are complicating this simple question, here how this work:
Answer = Length of the Train - Length of the platform
Length of the Train= Speed + Time (please refer the formula).
: 54 * 5/18 = 15(speed of the train)X 20 Time = 300
Length of the Platmform= Speed + Time
: 54 * 5/18 = 15 (Speed of the Train) X 36 Time = 540
So answer = 540 - 300 = 240 M
Answer = Length of the Train - Length of the platform
Length of the Train= Speed + Time (please refer the formula).
: 54 * 5/18 = 15(speed of the train)X 20 Time = 300
Length of the Platmform= Speed + Time
: 54 * 5/18 = 15 (Speed of the Train) X 36 Time = 540
So answer = 540 - 300 = 240 M
Roshan said:
7 years ago
Sol: speed of train in m/sec = 54*5/18.
=15 m/sec.
The total Distance of both = speed * time.
Platform and train =15 * 36 m
= 540m
And the Length of train = 20 * 15 m.
= 300m.
Plateform=(total distance - length of the train).
= (540 - 300) m,
= 240 m.
=15 m/sec.
The total Distance of both = speed * time.
Platform and train =15 * 36 m
= 540m
And the Length of train = 20 * 15 m.
= 300m.
Plateform=(total distance - length of the train).
= (540 - 300) m,
= 240 m.
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.
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