Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 25)
25.
A train 108 m long moving at a speed of 50 km/hr crosses a train 112 m long coming from opposite direction in 6 seconds. The speed of the second train is:
Answer: Option
Explanation:
Let the speed of the second train be x km/hr.
| Relative speed | = (x + 50) km/hr | |||||||
|
||||||||
|
![]](/_files/images/aptitude/1-sym-cbracket-h1.gif)
Distance covered = (108 + 112) = 220 m.
 |
220 | = 6 | ||
|
250 + 5x = 660
x = 82 km/hr.
Discussion:
77 comments Page 2 of 8.
Prity sahay said:
6 years ago
If everything is converted into m/s then the answer will also be 82m/s not 82 km/hr.
(1)
Ranjith said:
1 decade ago
Total distance of the 2 trains are 220 (108+112) :first don't change anything. Just change the speed 50 km/hr into m/sec.
If we change speed 50 ino m/sec then it will be 125/9. The equation becomes.
(125/9) +x=220/6.
We get x=410/18 m/sec.
Now convert to km/hr we get x= (410/18) (18/5).
X=82.
If we change speed 50 ino m/sec then it will be 125/9. The equation becomes.
(125/9) +x=220/6.
We get x=410/18 m/sec.
Now convert to km/hr we get x= (410/18) (18/5).
X=82.
(1)
Sundar said:
2 decades ago
Hi Raj,
Please note that
At the first step we are taking the speed of the second train be x KM/HR.
At final step we are finding the value of 'x'.
So, the answer is 'x' km/hr.
Thats why the answer is in km/hr.
Please note that
At the first step we are taking the speed of the second train be x KM/HR.
At final step we are finding the value of 'x'.
So, the answer is 'x' km/hr.
Thats why the answer is in km/hr.
(1)
Prem said:
6 years ago
I agree with you. @Prity.
Ravi said:
9 years ago
Simple solution method:.
Length of train 1st is = 108m.
Speed of train 1st is = 50km/h => 50 * 5/18 == 125/9 m/sec.
Length of trian - 2nd is = 112m.
Now, let the speed of 2nd tarin is = x m/sec.
Relative speed =x + (125/9).
Relative distance = 108 + 112 = 220 m.
Time = 6 sec.
Now, s = d/t.
=> x + 125/9 = 220/6 (therefore 220/6= 110/3).
=> x = (110/3) - (125/9).
=> x = 205/9 m/sec (205/9) * (18/5).
x = 82 km/h answer.
Length of train 1st is = 108m.
Speed of train 1st is = 50km/h => 50 * 5/18 == 125/9 m/sec.
Length of trian - 2nd is = 112m.
Now, let the speed of 2nd tarin is = x m/sec.
Relative speed =x + (125/9).
Relative distance = 108 + 112 = 220 m.
Time = 6 sec.
Now, s = d/t.
=> x + 125/9 = 220/6 (therefore 220/6= 110/3).
=> x = (110/3) - (125/9).
=> x = 205/9 m/sec (205/9) * (18/5).
x = 82 km/h answer.
Dharamjeet Singh said:
1 decade ago
How can the final answer come in Km/hr ??
Arkadev said:
7 years ago
Relative speed =220/6 * 18/5=132.
Second trains speed =132-50 = 80.
Second trains speed =132-50 = 80.
Nagesh said:
7 years ago
Thank you @Das.
Gopal sunar said:
7 years ago
Thank you @Soumitra Das.
Nileshshelar said:
7 years ago
(Total distance covered) ÷ (net speed) = time.
Mtrs/(mtr/sec) = sec.
220/(50+x) * 5/18=6,
So x=82.
But the unit is now mtr/sec because all we have converted into mtrs and seconds.
Mtrs/(mtr/sec) = sec.
220/(50+x) * 5/18=6,
So x=82.
But the unit is now mtr/sec because all we have converted into mtrs and seconds.
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