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?
230 m
240 m
260 m
320 m
None of these
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.

Krishna said:   9 years ago
Thanks Indiabix, because of this discussion section I can understand that tricks.

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?

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.

Reeha said:   7 years ago
Relative speed is to be found when two moving objects or trains are given.

Pari said:   7 years ago
If we want to find kmph means 15/8.
mph means 8/15 simple formula.

Sam said:   8 years ago
Explain the following step.

x+270/9 = 500/9.

Murugan said:   8 years ago
@Sam.

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.


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