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:
106 comments Page 3 of 11.
Prashant said:
1 decade ago
Please clear my doubt.
Let the train pass after t time.
So train has to cover (120+240+x)/45 in t time.
And jogger covers x/9 in t time.
(120+240+x) /45 = x/9.
Answer is 90 sec but logic is correct that they both meet after t time.
Let the train pass after t time.
So train has to cover (120+240+x)/45 in t time.
And jogger covers x/9 in t time.
(120+240+x) /45 = x/9.
Answer is 90 sec but logic is correct that they both meet after t time.
Shubham singh said:
10 years ago
Suppose jogger is running at 18 kmph and rest things are same so according to the calculation as done in explanation time should be 360/(15/2) = 48 sec but in that time jogger have also run 48*5 = 240 m so yet 120 m ahead of train.
Rahul said:
10 years ago
The jogger is not idle eight, I think it is wrong because the jogger will run at a speed of 9 kmph during the time the train passes him so this distance should also be covered I solution but it is not the answer would be 48 sec.
Md Ashique said:
1 decade ago
@Manish kumar mina.
Yeah you are right. We are not finding the time w.r.t platform, its w.r.t the man, who is moving with 9kmph, so the total distance will be 120+0=120 and required time will be (120+0) / (45-9) =12 sec.
Yeah you are right. We are not finding the time w.r.t platform, its w.r.t the man, who is moving with 9kmph, so the total distance will be 120+0=120 and required time will be (120+0) / (45-9) =12 sec.
RPrabha said:
2 decades ago
If in both the objects move in the same direction, the relative speed would be the sum of both the speeds. How is calculation is done. Even if tried with the mentioned procedure, the options don't have the derived answer
Abhishek said:
6 years ago
The jogger is ahead of the train by 240m and the question asks us to find the time train takes to pass the jogger, should we consider the time taken to cover distance of 240m and then add time take to cross the jogger.
Prerna said:
1 decade ago
Do we suppose to pass the platform too. If jogger is also moving there is no point in considering the jogging track length.
Relative speed is 10 m/s hence to pass the train of length 120m we will need only 12 sec.
Relative speed is 10 m/s hence to pass the train of length 120m we will need only 12 sec.
Viji.T said:
1 decade ago
The distance taken here is not clear for me. They use the term ahead of the engine like that. What they mean there. To take a distance as (120+240) , what is the logic behind that. Please can anyone explain me?
Mayur said:
7 years ago
Why we are considering full length of the platform as 240m?
It is very much possible that the train will cross the jogger before the platform (240m) is fully covered.
Then why total distance= 120m+240m?
It is very much possible that the train will cross the jogger before the platform (240m) is fully covered.
Then why total distance= 120m+240m?
Jay said:
1 decade ago
Relative speed concept when two object moves in same direction than their speed is equal to the subtraction of their actual speed. Relative speed is a speed of one object with respect to another ok.
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