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 2 of 7.
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.
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
Pramod said:
1 decade ago
Two trains are in opposite travelling in the opposite direction. So how can can add their length? It has to be be subtraction. If they are moving in the same direction then add only.
Karn sharma said:
1 decade ago
Trains are move in opposite direction. But out of speed n distance one quantity is subtract but in the solution of this question both are added. Please explain I can't understand.
Kpkpkp said:
1 decade ago
When two trains move in opp direction you cant add length. Because length of smallest train is common to both. The actual distance travelled will be length of large train only.
Silambuiks said:
1 decade ago
@Prasath.
5/18 means.
1 km = 1000 meter and 1hr = 3600 second.
Convert Kilometer per hour into Meter per second.
Divide the value of 1000/3600 its answer is 5/18.
5/18 means.
1 km = 1000 meter and 1hr = 3600 second.
Convert Kilometer per hour into Meter per second.
Divide the value of 1000/3600 its answer is 5/18.
Nareen said:
1 decade ago
Short cut Method
Relative speed = (120 + 80) km/hr
= 200 x 5/18 m/sec
= 500/9 m/sec.
= 500/9*9
= 500 m
= u+v = 500
= 270+v = 500
= 230m
Relative speed = (120 + 80) km/hr
= 200 x 5/18 m/sec
= 500/9 m/sec.
= 500/9*9
= 500 m
= u+v = 500
= 270+v = 500
= 230m
Sushma said:
1 decade ago
As given: 120+80=200
200*5/18=500/9
Let the length of other train be X
then X+270/9=500/9
cross multiply, u vl get
9X + 2430= 4500
9X=2070.
.'. X=2070/9
x=230
200*5/18=500/9
Let the length of other train be X
then X+270/9=500/9
cross multiply, u vl get
9X + 2430= 4500
9X=2070.
.'. X=2070/9
x=230
Mohit said:
4 years ago
L1 = 270, L2 =?.
T = D/S
S = 120+80Km/h, S = 200*5/28, S= 500/9,
T = 9 Second,
270 + L2/500/9 = 9,
L2 = 500 - 270,
2 = 230.
Length of 2nd train = 230 M.
T = D/S
S = 120+80Km/h, S = 200*5/28, S= 500/9,
T = 9 Second,
270 + L2/500/9 = 9,
L2 = 500 - 270,
2 = 230.
Length of 2nd train = 230 M.
(7)
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.
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