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 6 of 29.
Sahil said:
2 decades ago
Distance= speed*time
300=15*20
this is length of a train only and we have to find out length of a plateform so we add length of both train and plateform becoz in case of bridge or plateform we can add both the length.
then
x+300/36=15
=240m
300=15*20
this is length of a train only and we have to find out length of a plateform so we add length of both train and plateform becoz in case of bridge or plateform we can add both the length.
then
x+300/36=15
=240m
Sheik said:
2 decades ago
Me also have the same doubt.
Sahil,
Dis= s*t is okay.
Why didn't we take 300=15*36.
Please explain.
Sahil,
Dis= s*t is okay.
Why didn't we take 300=15*36.
Please explain.
Shiva said:
2 decades ago
How is that you have taken (15 x 20) m as train length?
Rajiv said:
2 decades ago
Why we do (15*20) ?
Siva krishna said:
2 decades ago
I have also same doubt explain me
Vetri said:
2 decades ago
Train passes 36 sec but man standing 20sec so (36-20=16)
speed= 15m/sec
length=16*15=240m
speed= 15m/sec
length=16*15=240m
Priya said:
2 decades ago
Yeah the answer must be C. 300m.
Sara said:
2 decades ago
We can take 15x20 as the train length only if the man is standing at the beginning of the platform. Am I correct.
Anj said:
2 decades ago
The answer is perfectly right and logical.
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.
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