Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 4)
4.
Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is:
Answer: Option
Explanation:
Let the speeds of the two trains be x m/sec and y m/sec respectively.
Then, length of the first train = 27x metres,
and length of the second train = 17y metres.
 |
27x + 17y | = 23 |
| x+ y |
27x + 17y = 23x + 23y
4x = 6y
| |
x | = | 3 | . |
| y | 2 |
Discussion:
233 comments Page 22 of 24.
Rekha Kondamangale said:
7 years ago
Formula is
The ratio of speed = ax+by /x+y.
The ratio of speed = ax+by /x+y.
Ramhari said:
7 years ago
In this question, there is no any data that two trains are equal length. A train has passed a man in 27 seconds and another has passed in 17. The second one might be faster or short in length. So, Both can happen.
Swaminathan said:
7 years ago
Hi,
According to me,
(27-23): (17-23),
4 : 6.
Am I right?
According to me,
(27-23): (17-23),
4 : 6.
Am I right?
Deb said:
7 years ago
We can solve by (27-23)/(23-17).
Vidhyadhar said:
7 years ago
Let x=speed of train 1.
And y=speed of train 2.
Our task=x/y.
So, length of 1st train (d1)=x*27(dist=speed*time)
So, 2nd (d2) = y * 17.
Time taken by trains to cross each other =23 sec.
Time =dist/speed.
23=(d1+d2)/x+y.
23=(27*x+17*y)/x+y.
By solving this we get.
Result = x/y = 3/2
And y=speed of train 2.
Our task=x/y.
So, length of 1st train (d1)=x*27(dist=speed*time)
So, 2nd (d2) = y * 17.
Time taken by trains to cross each other =23 sec.
Time =dist/speed.
23=(d1+d2)/x+y.
23=(27*x+17*y)/x+y.
By solving this we get.
Result = x/y = 3/2
Kavya said:
7 years ago
Good answer, Thanks @Shyam.
Ganapathi said:
7 years ago
Time taken by 1st train is more than the 2nd train then how speed ratio of 1st train is more than second train? I am not getting this. Please tell me.
ASHIS DAS said:
7 years ago
Agree @Ganapathi.
Please, anyone, give clearance.
Please, anyone, give clearance.
Nagendra said:
7 years ago
@Ganapathi, @Ashish Das,
The length of 1st Train is too long compared to 2nd Train. Hence even if though if it is faster, it took more time to cross the man.
The length of 1st Train is too long compared to 2nd Train. Hence even if though if it is faster, it took more time to cross the man.
Kumar said:
7 years ago
Distance = speed * time.
Time = 23 sec.
Time = total distance/speed,
Total distance = 27x+17y
The relative speed = x+y (opposite direction).
(27x+17y/x+y) = 23.
Time = 23 sec.
Time = total distance/speed,
Total distance = 27x+17y
The relative speed = x+y (opposite direction).
(27x+17y/x+y) = 23.
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