Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 10)
10.
A jogger running at 9 kmph alongside a railway track in 240 metres ahead of the engine of a 120 metres long train running at 45 kmph in the same direction. In how much time will the train pass the jogger?
Answer: Option
Explanation:
Speed of train relative to jogger = (45 - 9) km/hr = 36 km/hr.
| = |  |
36 x | 5 |  m/sec |
| 18 |
= 10 m/sec.
Distance to be covered = (240 + 120) m = 360 m.
 Time taken = |
|
360 | sec |
= 36 sec. |
| 10 |
Discussion:
107 comments Page 7 of 11.
Sandeep said:
10 years ago
Can anyone explain by using formula a + b / u - v?
Priya said:
9 years ago
What is the unit digit of 991^45? Can anyone tell me?
Raaj said:
9 years ago
If the direction of both things is in the same direction then the relative speed will be subtracted but in the case of opposite direction, relative speed will be added.
Shubh said:
9 years ago
What will be the shortcut method if trains are moving in opposite directions?
Shubham said:
9 years ago
as (a+b/u-v).
(45-9) * 5/18 = 10m/s.
(120 + 240/10) = 36s.
(45-9) * 5/18 = 10m/s.
(120 + 240/10) = 36s.
Raj vora said:
9 years ago
Can you please explain why we have to add 240 + 120?
Neerja said:
9 years ago
@Raj Vora.
The distance between the jogger and train is 240m so to first catch up to the jogger the train has to travel 240m. The length of the train is 120m so to completely pass the man and overtake him the train has to travel the length of the train, i.e. 120m.
Therefore total distance to be travelled by the train is 120m+240m=360m.
Hope this helped.
The distance between the jogger and train is 240m so to first catch up to the jogger the train has to travel 240m. The length of the train is 120m so to completely pass the man and overtake him the train has to travel the length of the train, i.e. 120m.
Therefore total distance to be travelled by the train is 120m+240m=360m.
Hope this helped.
Shubhankar said:
9 years ago
Jogger is also moving, I don't think answer is correct please update we have to first come to a meeting point of train and the jogger.
Adarsh said:
8 years ago
Relative speed can be used only when the jogger covers 240 m in the said time. But he already is 240 m ahead of the train. Jogger is also moving, so he might also cover some distance, we have to calculate his distance. And we have to add that distance x +240 m + 120 meter. We have no idea about this distance x right?
Mohit Tiwari said:
8 years ago
The relative speed is 10m/s. But train needs to cover 240+2*(length of train) to pass the jogger so the answer should be 48 m/s.
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