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:
240 comments Page 16 of 24.
K.kiran kumar said:
2 decades ago
I can't get this step
(27x+17y) / (x+y) = 23
Why we have to use this? can any one explain me.
(27x+17y) / (x+y) = 23
Why we have to use this? can any one explain me.
RAVI said:
1 decade ago
I can't get this step
(27x+17y) / (x+y) = 23
Why we have to use this? can any one explain me.
(27x+17y) / (x+y) = 23
Why we have to use this? can any one explain me.
Amit Jana said:
1 decade ago
#Krishna no this is not possible as you say. Then cross each other in 23 sec. Is have no sense?
Sourabh yadav said:
1 decade 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:
7 years ago
The explanation are excellent, but we asked the the speed, so why we calculated the time taken?
Dripta Majumdar said:
1 year ago
Why is the length of the platform not taken into consideration? Anyone, please explain to me.
(11)
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:
9 years ago
(x+y) I am not understanding that where this comes here this question, please give answer.
Aditya said:
7 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:
7 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)
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