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 5 of 28.
Guravareddy said:
7 years ago
Given data is U is 36 sec V 20 secc speed is 54 km/h.
Convert the speed from km/h to m/s,
54*5/18 = 270/18 = 15m/sec,
relative speed of train in same direction ( U - V),
= 36 - 20 = 16.
now,
speed = dist/time ( s = d/t).
here we find the dist.
so,
D=S*T.
Now we have speed & time.
D=15*16 = 240m.
Convert the speed from km/h to m/s,
54*5/18 = 270/18 = 15m/sec,
relative speed of train in same direction ( U - V),
= 36 - 20 = 16.
now,
speed = dist/time ( s = d/t).
here we find the dist.
so,
D=S*T.
Now we have speed & time.
D=15*16 = 240m.
Udaya said:
5 years ago
Shortcut method:-
Train + Platform = 36 sec.
Train = 20sec.
Extra it takes 16 sec to travel platform.
Covert kmph to m/s because we need answer in m/ s.
54kmph*5/18 = 15m/s.
15* 20 = 300m train length.
It takes 20 sec ---> 300m
16sec ---> ?????
Less by more concept 16/20 *300 = 240 m.
Train + Platform = 36 sec.
Train = 20sec.
Extra it takes 16 sec to travel platform.
Covert kmph to m/s because we need answer in m/ s.
54kmph*5/18 = 15m/s.
15* 20 = 300m train length.
It takes 20 sec ---> 300m
16sec ---> ?????
Less by more concept 16/20 *300 = 240 m.
(2)
Aditya said:
5 months ago
540 is the total distance that includes train length+ and platform length.
Here we need only platform length that's why we need train length or you can get another approach like 36-20=16sec. It's the time of starting of the train and the starting of exist platform 15 meters per sec * 16 sec = 240 meters.
Here we need only platform length that's why we need train length or you can get another approach like 36-20=16sec. It's the time of starting of the train and the starting of exist platform 15 meters per sec * 16 sec = 240 meters.
(8)
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.
Rejwan Hossain said:
3 years ago
The length of the platform = (speed of train * time taken to pass the platform)/(1 - (time taken to pass the man/time taken to pass the platform))
In this case:
The length of platform = (54 * 36)/(1 - (20 / 36))
= (54*36)/(1-(20/36))
= (1944)/(1-(5/9))
= 1944/(4/9)
= 1944 * (9/4) = 240 meters.
In this case:
The length of platform = (54 * 36)/(1 - (20 / 36))
= (54*36)/(1-(20/36))
= (1944)/(1-(5/9))
= 1944/(4/9)
= 1944 * (9/4) = 240 meters.
(11)
Revanth said:
6 years ago
Given
t(p) =36s.
t(m)=20s.
Speed of the train = 54km/hr.
As we all know that speed = distance/ time.
Now, we have to convert the speed in m/s.
So, 54*5/18=15 m/s.
S=d/t => l/t.
L(t)= s*t => 15 m/s * 20s = 300m,
Now l(t)+l(b)= 15 m/s * 36s,
300m + l(b) = 540m.
L(b) = 540-300,
L(b)= 260 m.
t(p) =36s.
t(m)=20s.
Speed of the train = 54km/hr.
As we all know that speed = distance/ time.
Now, we have to convert the speed in m/s.
So, 54*5/18=15 m/s.
S=d/t => l/t.
L(t)= s*t => 15 m/s * 20s = 300m,
Now l(t)+l(b)= 15 m/s * 36s,
300m + l(b) = 540m.
L(b) = 540-300,
L(b)= 260 m.
Uttam Roy said:
1 month ago
The speed of train = 54 x 5/18m/s,
= 15m/s.
Length of train = 15 x 20 = 300 meters ∴( distance = speed x time),
Total length = 15 x 30 = 540 (length of train x platform time taken to reach out),
The final answer is 540 - 300 meters.
= 240 meters.
= 15m/s.
Length of train = 15 x 20 = 300 meters ∴( distance = speed x time),
Total length = 15 x 30 = 540 (length of train x platform time taken to reach out),
The final answer is 540 - 300 meters.
= 240 meters.
(7)
Praveen said:
2 years ago
36sec it passes both man and platform but they ask only for platform so we have to deduct man standing passes 20sec.
36-20 = 16sec it passes only for the platform.
Then find out using this formula;
Distance = speed * time.
We know speed = 54km/hr.
Time = 16sec.
D = 54*5/18 m/sec.
D = 240m.
36-20 = 16sec it passes only for the platform.
Then find out using this formula;
Distance = speed * time.
We know speed = 54km/hr.
Time = 16sec.
D = 54*5/18 m/sec.
D = 240m.
(57)
Satish said:
8 years ago
Let distance be x m.
Time take for crossing platform=36sec.
For a man on the same platform=20 sec.
Speed=D/T, we get speed of train=54*5/18=15m/sec.
Since the man is on the same platform we can subtract the time from entire time=36-20=16
So, S=D/T
15=x/16.
Then, x=15*16=240m.
That's all.
Time take for crossing platform=36sec.
For a man on the same platform=20 sec.
Speed=D/T, we get speed of train=54*5/18=15m/sec.
Since the man is on the same platform we can subtract the time from entire time=36-20=16
So, S=D/T
15=x/16.
Then, x=15*16=240m.
That's all.
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.
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