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 7 of 7.
Pankaj kumar marskole said:
1 decade ago
Time taken crossed the train=length of the both train/length of the speed.
Let length of the 2nd train is x.
9= (270+x)/(100/3+200/9).
X=230.
Let length of the 2nd train is x.
9= (270+x)/(100/3+200/9).
X=230.
Arulmozhi said:
1 decade ago
Hai friends,
Having any other shortcut method to this problem?
Having any other shortcut method to this problem?
Randhir said:
1 decade ago
If two trains of length a metres and b metres are moving in opposite directions at u m/s and v m/s, then:
The time taken by the trains to cross each other =(a+b)/(u+v)
Then time is 9 sec, a=270 metres, b=x metres, u=120 kmph,
v=80 kmph
Therefore 9=(270+x)/(120+80)*5/18
we multiply (120+80) by 5/18 because converting kmph into m/sec
5/18*200*9=270+x
x=230
The time taken by the trains to cross each other =(a+b)/(u+v)
Then time is 9 sec, a=270 metres, b=x metres, u=120 kmph,
v=80 kmph
Therefore 9=(270+x)/(120+80)*5/18
we multiply (120+80) by 5/18 because converting kmph into m/sec
5/18*200*9=270+x
x=230
Pavan said:
1 decade ago
Why you add X and 270 ?
Ajantha said:
2 decades ago
Hi meenu,
Total speed(Relative speed) of two trains=120+80=200km/hr
we derived this from km/hr to meter/sec
=200*5/18 (bcas1000/3600=5/18)
=1000/18
=500/9
Total speed(Relative speed) of two trains=120+80=200km/hr
we derived this from km/hr to meter/sec
=200*5/18 (bcas1000/3600=5/18)
=1000/18
=500/9
Meenu said:
2 decades ago
In this solution how you are multiplying 5/18 with 200.
I can't understand that wll you please explain me that.
I can't understand that wll you please explain me that.
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