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:
237 comments Page 16 of 24.
Sourabh yadav said:
10 years ago
An alternative answer:
27 - 23 = 4.
27 - 17 = 6.
Take the square root of both 6 and 4
=> 3:2.
27 - 23 = 4.
27 - 17 = 6.
Take the square root of both 6 and 4
=> 3:2.
Abraham said:
6 years ago
The explanation are excellent, but we asked the the speed, so why we calculated the time taken?
Dripta Majumdar said:
8 months ago
Why is the length of the platform not taken into consideration? Anyone, please explain to me.
(10)
Sharad said:
1 decade ago
@James.
27x+17y = 23x+23y.
27x-23x = 23y-17y.
4x = 6y.
4x/2 = 6y/2.
2x = 3y.
x/y = 3/2.
27x+17y = 23x+23y.
27x-23x = 23y-17y.
4x = 6y.
4x/2 = 6y/2.
2x = 3y.
x/y = 3/2.
Mayank Yadav said:
8 years ago
(x+y) I am not understanding that where this comes here this question, please give answer.
Aditya said:
6 years ago
Distance is not relative why we add both the lengths?
We should only take either of them.
We should only take either of them.
Kamanulla said:
6 years ago
A = 27 - 23sec = 4sec.
B = 23 - 17sec = 6sec.
A:B = 4:6 = 2:3 in Sec.
A:B = 3:2 in Speed.
B = 23 - 17sec = 6sec.
A:B = 4:6 = 2:3 in Sec.
A:B = 3:2 in Speed.
(1)
Ajit said:
1 decade ago
Dear rohit,
Your calculation right but this furmula use in every cases or limited case?
Your calculation right but this furmula use in every cases or limited case?
Anil Bhadani said:
8 years ago
Its very shortcut and its very simple.
27-23 = 4
23-17 = 6
so,4:6 = 2:3 or 3:2 also.
27-23 = 4
23-17 = 6
so,4:6 = 2:3 or 3:2 also.
Narayan said:
1 decade ago
27 17
23
23-17=6 27-23=4
Then ratio become 3:2
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