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:
234 comments Page 12 of 24.
Anil vattamwar said:
1 decade ago
Train1 time is = 27.
Train2 time is = 17.
Divide them = (27/17) => (3/2).
Train2 time is = 17.
Divide them = (27/17) => (3/2).
Chacko said:
1 decade ago
Can anyone say why is 27X+17Y = 23X+23Y....?
Ideally if we cross multiply, it should come as 27x+17Y = 23X-23Y.
Ideally if we cross multiply, it should come as 27x+17Y = 23X-23Y.
Kriti said:
1 decade ago
How can the time be taken as the ratio for length?
I mean why 27x and 17y. 27 and 17 are time, then how can they be taken as ratios of length?
I mean why 27x and 17y. 27 and 17 are time, then how can they be taken as ratios of length?
Anil said:
1 decade ago
If, 4x=6y.
Then how to come ratio 3:2?
How it possible?
Then how to come ratio 3:2?
How it possible?
Azhagarsamy said:
1 decade ago
Simple @Anil.
4x = 6y.
Then x/y = 6/4.
x/y = 3/2.
Therefore the ratio is 3:2.
4x = 6y.
Then x/y = 6/4.
x/y = 3/2.
Therefore the ratio is 3:2.
Tamil said:
1 decade ago
Hi friends.
How to use mod method to calculate this problem?
How to use mod method to calculate this problem?
Cherry said:
1 decade ago
Can any one say how does this length of the first and second trains are considered as 27x and 17y respectively?
Rajkumar said:
1 decade ago
It is very simple to understand the logic of 27x+17y/x+y=23 first we came across to know logic first of all we know the, speed=x/t in this way we assume that the sum of the two train lengths divided by assuming speeds is equal to relative crossing time is 23 seconds.
One of the question arise in your mind that is why we took length s of trains in sum because they cross each other with respect to man.
Thank you.
One of the question arise in your mind that is why we took length s of trains in sum because they cross each other with respect to man.
Thank you.
Rajkumar said:
1 decade ago
Dear friend cherry the logic is very simple to understand we know speed = distance/time in this way 27 is the time of one train to pass a man and "x"is the assuming speed I hope to you may be understand.
Pradeep kumar said:
1 decade ago
Also calculate as train 1 = 27sec.
Train 2 = 17sec.
Ratio of train 1 & train 2.
27/17 = 1.588.
We have an option 3/2 = 1.5.
Train 2 = 17sec.
Ratio of train 1 & train 2.
27/17 = 1.588.
We have an option 3/2 = 1.5.
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