Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 26)
26.
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?
Answer: Option
Explanation:
| Relative speed = (40 - 20) km/hr = |  |
20 x | 5 |  |
m/sec = | |
50 | |
m/sec. |
| 18 | 9 |
 Length of faster train = |
|
50 | x 5 | |
m = | 250 | m = 27 | 7 | m. |
| 9 | 9 | 9 |
Discussion:
72 comments Page 5 of 8.
Manish said:
9 years ago
We can't find the slower train length as it will never pass the faster train.
So in order two find slower train length we need how much time the faster train take to pass the slower train not the man.
Relative means that slower is still.
So in order two find slower train length we need how much time the faster train take to pass the slower train not the man.
Relative means that slower is still.
(1)
Azim said:
9 years ago
Consider the slower train as a man.
Swati said:
8 years ago
Why do we ignore the length of the slower train, Is it because the place where the man is sitting is not fixed?
Hrushi said:
8 years ago
Please explain clearly. Why we ignore the length of the slow train?
Nilesh z. said:
8 years ago
Just consider that man is moving at 20 km/hr. Now solve the problem as you solved problem number 27 by considering just one man. You will come to know why we don't consider the length of the slower train.
Priyansh patidar said:
8 years ago
50/9 = x/5,
X=250/9,
X=27 7/9.
X=250/9,
X=27 7/9.
Ujjwal said:
8 years ago
Use the concept of relative speed i.e. slower train is fixed and the faster train is moving with the speed of (40-20)km/hr=20km/hr. Then the men sitting in the slower train is also a stationary one wrt. faster train .then simply use the formula of a train moving with a velocity of 20 km/hr to pass a stationary object in 5 seconds.
MiniPanda said:
8 years ago
The relative speed b/w the train is 20kmph. It is easier to understand if you look in this way-- The faster train is moving at a speed of 20kmph and the slower train is 0kmph i.e. static. So now since the person sitting inside the train is also static we can simply treat this problem like "the time taken by a train to cross a pole" type.
GAURAV said:
8 years ago
How can we assume the man will be sitting on a forehead of the train? He can be sitting anywhere in the train.
I think the answer will be can't be determined until exact location of man is not mentioned.
I think the answer will be can't be determined until exact location of man is not mentioned.
Salman said:
8 years ago
The question focus on the fast train and the man sitting somewhere in the train.
Here we can consider the slow train as a man running with 20km/hr.
So now the question can be understood in this way as well:.
There is a train running at speed of 40km/hr and a man running with 20km/hr in the same direction of the train. Calculate the length of the train?
Now solve it. Hope now it will become easy for everyone.
Here we can consider the slow train as a man running with 20km/hr.
So now the question can be understood in this way as well:.
There is a train running at speed of 40km/hr and a man running with 20km/hr in the same direction of the train. Calculate the length of the train?
Now solve it. Hope now it will become easy for everyone.
(1)
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers