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:
282 comments Page 17 of 29.
Manoj Dhawade said:
1 decade ago
We have to do 15*36 because train crosses the platform in 36 sec. So the answer should be 300 m.
Harshini said:
1 decade ago
We have the formula.
Distance = Speed*Time.
= 15*20
= 300
Distance = Speed*Time.
= 15*20
= 300
Chinu said:
1 decade ago
Please explain why we took x+300?
Sunil Ranjan Samantaray said:
1 decade ago
Why length of the train will be 15*20 = 300?
Why not, length of train will be 15*36 = 540?
Please justify the reason.
Why not, length of train will be 15*36 = 540?
Please justify the reason.
Bharat said:
1 decade ago
v=d/t;. 15=d/36; d=540.
v=d/t ; 15=d/20 = d=300;
540-300 = 240.
v=d/t ; 15=d/20 = d=300;
540-300 = 240.
Mvk said:
1 decade ago
S (km/hr to m/s) => 54 * 5/18 = 15.
T = (36s - 20s) = 16s.
D = S * T = 15 * 16 = 240m.
T = (36s - 20s) = 16s.
D = S * T = 15 * 16 = 240m.
Juhi said:
1 decade ago
Instead of multiplying 15*20.
We can directly do it by method.
Firstly converting speed = 54*5/18 = 15 m.
Then as we know speed = distance/time.
Since distance = speed *time = 15(36-20) = 15*16 = 240m.
We can directly do it by method.
Firstly converting speed = 54*5/18 = 15 m.
Then as we know speed = distance/time.
Since distance = speed *time = 15(36-20) = 15*16 = 240m.
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.
RKK said:
1 decade ago
Speed = 54*(5/18) m/sec. = 15 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 = 540.
Ans = 240 m.
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 = 540.
Ans = 240 m.
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.
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