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 5 of 7.
Ash said:
9 years ago
Please explain this step 500/9 * 9.
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?
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.
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)
Srujana said:
8 years ago
Why we writing denominator 9 for x+270?
(1)
Sam said:
8 years ago
Explain the following step.
x+270/9 = 500/9.
x+270/9 = 500/9.
Murugan said:
8 years ago
@Sam.
Use this formula distance/time = speed.
Use this formula distance/time = speed.
Sathish said:
8 years ago
Another train's speed and time is already given from that we can calculate the trains length easily why we go for oppostie train?
Gaurav said:
8 years ago
Relative speed is 120 +80 =200.
Now l =s*t =200*5/18*9=500,
Now, the total dist minus 500-270=230m.
Now l =s*t =200*5/18*9=500,
Now, the total dist minus 500-270=230m.
Umar bodha said:
8 years ago
Trains running in opp directions.
Relative speed 120+80 =200.
By converting into m/s,
200*5÷18 =500/,
We know by formula
L=s*t.
Let x be the length of another train
Therefore
X+270=500÷9*9.
X=500-270= 230.
So, x=230m.
Relative speed 120+80 =200.
By converting into m/s,
200*5÷18 =500/,
We know by formula
L=s*t.
Let x be the length of another train
Therefore
X+270=500÷9*9.
X=500-270= 230.
So, x=230m.
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