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 3 of 6.
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.
Rosy said:
7 years ago
Please cam someone explains me again?
Arjun said:
6 years ago
Let x be the length of train.
Therefore speed of train = x/15 m/sec.
x+100 = (x/15) m/sec * 25 sec.
3x+300 = 5x.
x = 300/2 =150 m.
Therefore speed of train = x/15 m/sec.
x+100 = (x/15) m/sec * 25 sec.
3x+300 = 5x.
x = 300/2 =150 m.
Sanjana said:
6 years ago
Good explanation.
Madhan said:
6 years ago
Thanks all.
Gugi said:
5 years ago
Explain the answer, please.
Pavan.k said:
1 decade ago
Let length =x
Case 1: speed of train in 15 sec. =x/15
Case 2: since it crossed pole then the total distance = 100+x
Now speed =100+x/25
Now equating both the speeds x/15 = 100+x/25 we get the x value
Case 1: speed of train in 15 sec. =x/15
Case 2: since it crossed pole then the total distance = 100+x
Now speed =100+x/25
Now equating both the speeds x/15 = 100+x/25 we get the x value
MOHANRAJ.A said:
2 decades ago
Assume that length is x meters.
Speed y m/sec, speed=distance/time
so, y=x/15.------------------------1.
Like the same calculate after crossing the platform
y=x+100/25--------------------2
LHS equal. So
x+100/25=x/15;
15(x+100)=25x
Then remaing sme as above.
Speed y m/sec, speed=distance/time
so, y=x/15.------------------------1.
Like the same calculate after crossing the platform
y=x+100/25--------------------2
LHS equal. So
x+100/25=x/15;
15(x+100)=25x
Then remaing sme as above.
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