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 24 of 29.
Satheesh.m said:
1 decade ago
Speed as we calculated 15m/sec
The difference from the ref pt (i.e.,man) to the train pass the platform is 16
So, 15*16=240m
The difference from the ref pt (i.e.,man) to the train pass the platform is 16
So, 15*16=240m
Pawan said:
1 decade ago
It is longest but easy to undertand
len = speed*time
speed: 54*5/18=15
Now calculate the length of train,
len=15*20
=300
now calculate the length of platform
use same formula (x=platform length)
300+x=15*36
x=540-300
x=240
len = speed*time
speed: 54*5/18=15
Now calculate the length of train,
len=15*20
=300
now calculate the length of platform
use same formula (x=platform length)
300+x=15*36
x=540-300
x=240
Manonmani said:
1 decade ago
I also having doubt.
Why we took 20 sec (300=20*15).
Instead of 30sec (450=30*15).
Why we took 20 sec (300=20*15).
Instead of 30sec (450=30*15).
Tara said:
1 decade ago
The above answer can be solved by Jagadeesh & Verti given method, i thinkg its also rite.
Sanjay punj said:
1 decade ago
Thanks sachin kamble.
Vivek said:
1 decade ago
Why we have multiplied with 20 means ... we have to take any one of the reference point. 36sec is train PASSES a station platform so we cant take. but here we can take it because man STANDING on the platform in 20 seconds. STANDING POINT is take it as reference point for calculating lengh of train.
Sachin kamble said:
1 decade ago
Train passes the plat form in 36 sec and man standing on platform i.e 20 sec so the time 16 sec by 36-20=16 then apply speed=distance/time we have speed 54km/hr that to be converted in to m/sec because we need length in meter. So 54*[5/18] = 15 m/sec.
Then distance = 16*15 = 240.
Then distance = 16*15 = 240.
Suresh said:
1 decade ago
Satheesh your answer is very easy and simple way of maintain the problem solution. Thank you.
Sabarish said:
1 decade ago
@saikiran
here speed of the train given as in km/hr . so first we convert it into m/sec [i.e 54km/hr*(5/18)=15m/sec]. 5/18 is used to convert train speed into m/sec.
Then if you want length of the train means,you;ll use below formula:
Length of the Train=Speed*time
It is general formula in train based questions..
Have a nice day for you..
here speed of the train given as in km/hr . so first we convert it into m/sec [i.e 54km/hr*(5/18)=15m/sec]. 5/18 is used to convert train speed into m/sec.
Then if you want length of the train means,you;ll use below formula:
Length of the Train=Speed*time
It is general formula in train based questions..
Have a nice day for you..
Sid said:
1 decade ago
Satheesh your answer is simply super. Thank you.
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