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 15 of 24.
Smnk said:
9 years ago
Guys!
Difference between the 23s and 27s is 4 and,
Difference between the 23s and 17s is 6 of other train.
So, the ratio is 4 and 6.
Difference between the 23s and 27s is 4 and,
Difference between the 23s and 17s is 6 of other train.
So, the ratio is 4 and 6.
Mukesh said:
9 years ago
Total distance / total speed = total time.
This is the simple solution (X + Y) = relative speed.
Trains comes towards each other.
This is the simple solution (X + Y) = relative speed.
Trains comes towards each other.
P S said:
9 years ago
Another approach by looking at answers, in question, 27 come first and 17 come later so in answer bigger number will come first and smaller later, that option is "B" only, so we can find answer without going for actual calculation.
Heisenberg said:
9 years ago
Thanks @Narayan.
=> Guys use the method of mixture and allegation the answer is very much easy.
=> Guys use the method of mixture and allegation the answer is very much easy.
Shrikant said:
9 years ago
@Narayan.
Your answer is good it is a bit easy method.
Your answer is good it is a bit easy method.
Sarat said:
9 years ago
TIME = DISTANCE /SPEED.
We don't know how much distance apart
27x is train1 distance at which it crosses man
17y is 2nd train.
We know when they meet 23 sec.
23 = 27x + 17y/ x + y.
We don't know how much distance apart
27x is train1 distance at which it crosses man
17y is 2nd train.
We know when they meet 23 sec.
23 = 27x + 17y/ x + y.
Arifshaikh said:
9 years ago
Try the rule of alligation.
It will take 30 sec.
It will take 30 sec.
Harry said:
9 years ago
I don't know its correct or not but I got the answer easily.
My step-- it's not telling about the speed so what we have here is 27 sec and 17 sec so its the ratio 27:17.
(27/9) = 3 : (17/9) =1.8 = 2.
So I got 3 : 2.
I don't know whether its right step or not, Please correct me, if it is wrong.
My step-- it's not telling about the speed so what we have here is 27 sec and 17 sec so its the ratio 27:17.
(27/9) = 3 : (17/9) =1.8 = 2.
So I got 3 : 2.
I don't know whether its right step or not, Please correct me, if it is wrong.
Phani said:
9 years ago
23 - 17 = 6.
27 - 23 = 4.
6 : 4 = 3 : 2.
27 - 23 = 4.
6 : 4 = 3 : 2.
Yarasani srinivas said:
9 years ago
TIME = DISTANCE /SPEED.
We don't know how much distance apart.
27x is train1 distance at which it crosses man.
17y is a 2nd train.
We know when they meet 23 sec.
23 = 27x + 17y/ x + y.
We don't know how much distance apart.
27x is train1 distance at which it crosses man.
17y is a 2nd train.
We know when they meet 23 sec.
23 = 27x + 17y/ x + y.
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