Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 19)
19.
A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is:
Answer: Option
Explanation:
Let the length of the train be x metres and its speed by y m/sec.
| Then, | x | = 15  y = |
x | . |
| y | 15 |
 |
x + 100 | = | x |
| 25 | 15 |
15(x + 100) = 25x
15x + 1500 = 25x
1500 = 10x
x = 150 m.
Discussion:
55 comments Page 4 of 6.
Babu Tunk said:
9 years ago
Simplest way to solve this.
A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds.
Its length is:
Train speeds past a pole in 15 (distance/length unknown).
Train speeds past a platform of 100 m in 25 sec. it take 10 sec more to cross 100 m so to find out how much will it travel in 15 seconds is easy.
15 x 100/10 = 150.
Answer is 150 meters
Hope it helps you.
A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds.
Its length is:
Train speeds past a pole in 15 (distance/length unknown).
Train speeds past a platform of 100 m in 25 sec. it take 10 sec more to cross 100 m so to find out how much will it travel in 15 seconds is easy.
15 x 100/10 = 150.
Answer is 150 meters
Hope it helps you.
Seersha said:
9 years ago
We know, suppose speed = x & length = L.
L/15 = x.
Or L = 15 x.
Now,
(L +100) / 25 = x.
Can we substitute for L here.
(15 x + 100) / 25 = x.
15 x + 100 = 25 x.
100 = 10 x.
X = 10.
L = 15 * 10 = 150.
L/15 = x.
Or L = 15 x.
Now,
(L +100) / 25 = x.
Can we substitute for L here.
(15 x + 100) / 25 = x.
15 x + 100 = 25 x.
100 = 10 x.
X = 10.
L = 15 * 10 = 150.
Shirish said:
9 years ago
Why are you adding the length of the platform and length of the train X+100?
In the question, the distance between pole and platform is nowhere mentioned.
In the question, the distance between pole and platform is nowhere mentioned.
Dhiru said:
9 years ago
Speed of train = length of platform/difference of time.
= 100/(25 - 15) = 10km/h.
Then distance=speed * time.
= 10 * 15 = 150 m.
= 100/(25 - 15) = 10km/h.
Then distance=speed * time.
= 10 * 15 = 150 m.
Swap said:
9 years ago
Suppose the length of the train is X.
Therefore speed X/15,
As given 25 * X/15 = 100 + X,
25X = 1500 + 15X,
25X - 15X = 1500,
10 X = 1500,
X = 150.
Therefore speed X/15,
As given 25 * X/15 = 100 + X,
25X = 1500 + 15X,
25X - 15X = 1500,
10 X = 1500,
X = 150.
Sangita said:
8 years ago
Why x multiply with 100 and exactly which formula is used here? Please, clearly explain this.
SANTOSH said:
8 years ago
Can we calculate the speed of the train by the length of platform and time taken by train to cross the platform?
Vaibhav said said:
8 years ago
I can't unable to understand it, please explain.
Ravanan said:
8 years ago
Consider, train length is x now we find out the speed s=d/t here train length is d so s=x/15
x/15=(100+x)/25,
25x=(100+x)*15,
25x=1500+15x,
25x-15x=1500,
10x=1500,
x=1500/10,
x=150m.
x/15=(100+x)/25,
25x=(100+x)*15,
25x=1500+15x,
25x-15x=1500,
10x=1500,
x=1500/10,
x=150m.
(1)
Rosy said:
7 years ago
Please cam someone explains me again?
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