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:
287 comments Page 7 of 29.
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
Frank said:
2 decades ago
Whenever u get two timings subtract the highest from the lowest.
Eg: 36 - 20 = 16
16*15 (after converting it to m/sec) = 240.
Eg: 36 - 20 = 16
16*15 (after converting it to m/sec) = 240.
Nagashree said:
2 decades ago
Here man is standing in the platform, and we have to calculate the length of platform.
Hence we hav to multiply by 20 & not by36. Man in platform is reference point to us.
Hence we hav to multiply by 20 & not by36. Man in platform is reference point to us.
Remy said:
2 decades ago
How come (300+x) /15?its not said the man stands at the beginning of platform. If hes somwhere in the middle how come we add the length of the train 300 m ?
Gaurang said:
2 decades ago
Amit thanks for answer correctly.
Magesh said:
2 decades ago
Guys listen.
Take a point as man standing on the platform. So the moving train pass the point at the time of 20 sec.
So, Length of the train = (15 x 20)m = 300 m.
Take a point as man standing on the platform. So the moving train pass the point at the time of 20 sec.
So, Length of the train = (15 x 20)m = 300 m.
Karthik said:
2 decades ago
Shortcut:
Minus the both time of the train to cross the platform as well as man (reference point).
T = 36 sec, t = 20 sec.
T - t = 16 sec.
With the normal formula Length = Speed * Time
(i.e) 15 m/s * 16 sec = 240 metres.
Minus the both time of the train to cross the platform as well as man (reference point).
T = 36 sec, t = 20 sec.
T - t = 16 sec.
With the normal formula Length = Speed * Time
(i.e) 15 m/s * 16 sec = 240 metres.
Shelly said:
2 decades ago
Thanks Rahul.
Vivek said:
2 decades ago
speed:- 54*5/18= 15 m/sec
length of the train:-15*20= 300 m.(distance= speed * time)
length of the platform:-x
Speed = Distance /Time
15=300+x/36
300+x=540
x=540-300
x=240
length of the train:-15*20= 300 m.(distance= speed * time)
length of the platform:-x
Speed = Distance /Time
15=300+x/36
300+x=540
x=540-300
x=240
Kranthi said:
2 decades ago
As they asked only platform length why isn't it 35X15=540...
why should we substract...??
why should we substract...??
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