Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 14)
14.
Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:
Answer: Option
Explanation:
| Relative speed = (60 + 40) km/hr = |  |
100 x | 5 |  m/sec |
= | |
250 | m/sec. |
| 18 | 9 |
Distance covered in crossing each other = (140 + 160) m = 300 m.
| Required time = | |
300 x | 9 | sec |
= | 54 | sec = 10.8 sec. |
| 250 | 5 |
Discussion:
42 comments Page 2 of 5.
Ajit said:
1 decade ago
By using formula,
t = a+b/u+v, (train running opposite direction).
= (140+160) m/(40+60) km/hr = 300 m/250/9 m/s.
Now, t = 10.8 s.
t = a+b/u+v, (train running opposite direction).
= (140+160) m/(40+60) km/hr = 300 m/250/9 m/s.
Now, t = 10.8 s.
Ankiita said:
1 decade ago
Because when we convert km/hr into m/sec we multiply by 1000 & divide by 3600 so 1000/3600 after cancellation gives 5/18.
Praveen Sharma said:
10 years ago
x = (300*9)/250.
x = 2700/250 {Cut zero by zero}
x = 270/25.
x = 54/5 {Both no. divided by 5}
x = 10.8 sec.
x = 2700/250 {Cut zero by zero}
x = 270/25.
x = 54/5 {Both no. divided by 5}
x = 10.8 sec.
Vel said:
1 decade ago
60+40=100 (relative speed) bcoz opposite direction know
and we have to convert km into m
=100*5/18
=250/9
and we have to convert km into m
=100*5/18
=250/9
Siva said:
9 years ago
In the question, it did not mention which train to considered faster or slower, so how to solve it?
(1)
Sumi said:
1 decade ago
and u r rite priyavel but its not the time but speed which is 100km/hr
Did u get that nisha?
Did u get that nisha?
Rupa said:
1 decade ago
If it comes to opposite direction distance is subtracted. Why it is added here?
Dharmendra said:
9 years ago
Why did you change 250/9 to 9/250 in the last calculation? Pease explain me.
Haripriya said:
8 years ago
How it will come 10.8? I am not getting the calculation. Please explain it.
Rajesh said:
1 decade ago
Me too still don't understand as how we got 5/18?
Any one can clarify.
Any one can clarify.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers