Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 11)
11.
A 270 metres long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. What is the length of the other train?
Answer: Option
Explanation:
Relative speed = (120 + 80) km/hr
| = |  |
200 x | 5 |  m/sec |
| 18 |
| = | |
500 | m/sec. |
| 9 |
Let the length of the other train be x metres.
| Then, | x + 270 | = | 500 |
| 9 | 9 |
x + 270 = 500
x = 230.
Discussion:
66 comments Page 3 of 7.
Sam said:
8 years ago
Explain the following step.
x+270/9 = 500/9.
x+270/9 = 500/9.
Srujana said:
8 years ago
Why we writing denominator 9 for x+270?
(1)
Nikita said:
8 years ago
Right. But in the question trains are running in opposite side.
So speed is subtracted ie 120-80 = 40.
Am I correct?
So speed is subtracted ie 120-80 = 40.
Am I correct?
(1)
Dalton said:
8 years ago
It's simple and just take it easy.
When two trains running on the same site then relative speed is add, running in opposite site then we subtract it.
When two trains running on the same site then relative speed is add, running in opposite site then we subtract it.
Swanand said:
9 years ago
Hi,
Can we do like this?
200 * 5/18 = 55.6
In above step is it correct or not, because after all post are look like step following.
200*5/18= 500/9 m/s .
Why not 200 * 5/18 = 55.6.
From above my step will be;
55.6 = (270+x)/6.
(270 + x) = 55.6 * 6 = 333.33.
x = 333.33 - 270 = 63.3 m.
Why not?
Can we do like this?
200 * 5/18 = 55.6
In above step is it correct or not, because after all post are look like step following.
200*5/18= 500/9 m/s .
Why not 200 * 5/18 = 55.6.
From above my step will be;
55.6 = (270+x)/6.
(270 + x) = 55.6 * 6 = 333.33.
x = 333.33 - 270 = 63.3 m.
Why not?
Ash said:
9 years ago
Please explain this step 500/9 * 9.
Krishna said:
9 years ago
Thanks Indiabix, because of this discussion section I can understand that tricks.
Hannan said:
9 years ago
It's simple and just take it easy.
When two trains running on the same site then relative speed is add, running in opposite site then we subtract it.
When two trains running on the same site then relative speed is add, running in opposite site then we subtract it.
Arun said:
9 years ago
When we add the relative speed when substract please tell me?
Swathi said:
9 years ago
Thanks alot. It is very helpful to me.
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