Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 29)
29.
A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is
Answer: Option
Explanation:
Let the length of the first train be x metres.
| Then, the length of the second train is |  |
x |  |
metres. |
| 2 |
| Relative speed = (48 + 42) kmph = | |
90 x | 5 | |
m/sec = 25 m/sec. |
| 18 |
 |
[x + (x/2)] | = 12 or | 3x | = 300 or x = 200. |
| 25 | 2 |
Length of first train = 200 m.
Let the length of platform be y metres.
| Speed of the first train = | |
48 x | 5 | |
m/sec = | 40 | m/sec. |
| 18 | 3 |
| (200 + y) x |
3 | = 45 |
| 40 |
600 + 3y = 1800
y = 400 m.
Discussion:
48 comments Page 4 of 5.
Syndhya said:
1 decade ago
Could anybody explain clearly. Please. I can't understand. Explain in a simple manner please.
Stuti said:
1 decade ago
I didn't understand any bit of the problem. Please some one do explain in an easy way :).
Raj said:
1 decade ago
Why should not we take length of second train as x and length of first train as 2x?
Suyash said:
7 years ago
Can anyone help me to get this step?
X+(x/2)/25=12==> 3X/2 =300 ==> X=200.
X+(x/2)/25=12==> 3X/2 =300 ==> X=200.
Chidu said:
9 years ago
Here, mentioning the 2nd train is not needed it is a straight forward question.
Dinesh said:
1 decade ago
Can any one explain why he took the 48 kmph in the length of the platform?
Sonu said:
1 decade ago
Can any one explain why should we consider second train length as "x/2"?
Monika said:
5 years ago
Not getting this clearly, please explain in detail.
Naveen said:
5 years ago
Why we didn't use the length of the second train?
(1)
Anu said:
10 years ago
Why he took first train length? Why can't second?
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