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 14 of 24.
Shree said:
1 decade ago
Its simple .
T = D/S
Therefore total distance = 27x+17y and total speed = x+y
Total time = 23
23= 27x+17y/x+y
T = D/S
Therefore total distance = 27x+17y and total speed = x+y
Total time = 23
23= 27x+17y/x+y
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.
Deepak said:
1 decade ago
@niveditha
Since both train crossing each other in 23s, so have to multiply 23 by sum of speed of both train.
Since both train crossing each other in 23s, so have to multiply 23 by sum of speed of both train.
Krishna said:
1 decade ago
If I divide speed of one train 27 divided by another its almost 1.5 can I choose 3:2. Is it a pure coincidence ?
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?
Eshu said:
2 decades ago
Since both the trains are moving in opposite direction. To find total we have to add the sum of train length.
Ashfaq said:
8 years ago
Distance /time = speed.
but here in solution
distance /time = time (i.e 23 seconds )
How it is possible?
but here in solution
distance /time = time (i.e 23 seconds )
How it is possible?
Samara said:
8 years ago
Let the distance of platform be x.
Then speed1= x/27-23 and speed2= x/23-17,
So, the ratio of speed is 3:2.
Then speed1= x/27-23 and speed2= x/23-17,
So, the ratio of speed is 3:2.
Shiv said:
4 years ago
Here is simple solution for this question.
When we take it as mixture;
23 - 17 = 6
27 - 23 = 4
6/4 i.e 3:2.
When we take it as mixture;
23 - 17 = 6
27 - 23 = 4
6/4 i.e 3:2.
(46)
Raj said:
9 years ago
Short-cut : Alligation method.
27 17
23
6 4
= 6 : 4 means 3 : 2 => Answer.
27 17
23
6 4
= 6 : 4 means 3 : 2 => Answer.
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