Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 9)
9.
Two trains are moving in opposite directions @ 60 km/hr and 90 km/hr. Their lengths are 1.10 km and 0.9 km respectively. The time taken by the slower train to cross the faster train in seconds is:
Answer: Option
Explanation:
Relative speed = (60+ 90) km/hr
| = |  |
150 x | 5 |  m/sec |
| 18 |
| = | |
125 | m/sec. |
| 3 |
Distance covered = (1.10 + 0.9) km = 2 km = 2000 m.
| Required time = | |
2000 x | 3 | sec = 48 sec. |
| 125 |
Discussion:
111 comments Page 3 of 12.
Crack said:
7 years ago
I know why 5/18 is calculate. But in this particular math they didn't mention anything related to meter. Only answer is given in second, so we should only convert hr to seconds right? why we converted the km also? train length and speed both are in km, also in answer there's no km unit, only second. So please explain this part.
Srinivas said:
7 years ago
Simply, the solution is;
2 km =2000.
=150 * 5/18 is 41.66.
So 2000/41.66 = 48.
2 km =2000.
=150 * 5/18 is 41.66.
So 2000/41.66 = 48.
Hsu Hsu said:
7 years ago
Why do you sum the relation speed of the train in the opposite direction?
If direction are same, will you sum?
Please, someone, explain to me, I need help!
If direction are same, will you sum?
Please, someone, explain to me, I need help!
(1)
Shalinwilson said:
8 years ago
No need to convert to m/s.
Because everything in m and h.
Simply relative speed = 60+90 = 150 km/h.
Distance = 1.1+9 = 2 km.
2/150 = .013 hr (in seconds its .013*60 *60 = 48 seconds.
Because everything in m and h.
Simply relative speed = 60+90 = 150 km/h.
Distance = 1.1+9 = 2 km.
2/150 = .013 hr (in seconds its .013*60 *60 = 48 seconds.
(2)
Ram said:
8 years ago
Guys, can anyone explain how 41.6666667 was turn into 125/3?
Tarek said:
8 years ago
Then the time taken by the faster train to cross the slower will be?
(1)
Sarang said:
9 years ago
Distance =speed*time,
1.10+.9=60+90*time,
2km=150km/h*time,
2000=150*5/18*time,
2000=750/18*time,
2000=41.66*time,
2000/41.66=time,
Time=48 s.
1.10+.9=60+90*time,
2km=150km/h*time,
2000=150*5/18*time,
2000=750/18*time,
2000=41.66*time,
2000/41.66=time,
Time=48 s.
(1)
Pankaj said:
9 years ago
Hi, the time taken by faster train to cross slower & time taken by slower train to cross faster will be same, right?
So why are we using relative speed formula for all the time. We can use a+b/u+v for calculating time.
So why are we using relative speed formula for all the time. We can use a+b/u+v for calculating time.
Raghu said:
9 years ago
2km, when converted using formula, gives 5/9 m/s which is giving the wrong answer. Someone please explain this to me.
Sainath said:
9 years ago
Then, What will be the time taken by faster train to cross slower train?
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