Interview

Aptitude Basics for Solving Problems on Trains


The Questions will involve one train or two trains; therefore read the question whether the question involves one train or two trains because you can decide what formula to use and solve quickly. The entire aptitude question on trains will contain any of these 5 questions. Note that sometimes trains are replaced by some other thing like a person, man, car … etc

 


Single Train Questions (2 Types of questions)


 

Question 1:

What is the time taken by a train of length ‘L’ metres and travelling at a speed of ‘S’ to pass a pole or a standing man or a signal post or some stationary object?


Explanation

  • The Question will contain length of the train ‘L’
  • Train’s speed ‘S’ will be given in terms of either km/hr or m/sec.

If speed is given in terms of Km/hr, always remember to convert  it to m/sec which can be done               by this formula: =S x (5/18) m/sec

  • You have to find the time taken by the train to pass the stationary object. Use this formula

             Time taken to pass the object= L/S sec

 

Question 2

What is the time taken by a train of length ‘L’ metres and travelling at speed of ‘S’ to pass a pole or a standing man or a signal post or some stationary object of Length ‘M’?


Explanation

  • The Question will contain length of the train ‘L’
  • Length of the object ‘M’
  • Train’s speed ‘S’ will be given in terms of either km/hr or m/sec.

If the speed is given in terms of Km/hr, always remember to convert it to m/sec which is done                  by this formula: =S x (5/18) m/sec

  • You have to find the time taken by the train to pass the object of length ‘M’. Follow this procedure

               1. You know this: Time taken to pass the object= L/S sec

               2. Make changes to the above formula in this way…

                   Time taken to pass the object of length ‘M’ = (L+M)/S sec

 


Two Train Questions (3 Types)


 

Question 3:

What is the taken by the two trains that are of length ‘a’ and ‘b’ respectively and travelling opposite to each other at a speed of ‘u’ and ‘v’ respectively to cross each other?


Explanation

  • The Question will contain two trains and its lengths as; ‘a’ of the first train and ‘b’ of the second train.
  • The speed of the trains will also be included  as ‘u’ as speed of the first train and ‘v’ as the speed of the second train

If the speed is given in terms of Km/hr, always remember to convert it to m/sec which is done by             this formula

For train 1:      =u x (5/18) m/sec an

For train 2:     = v x (5/18) m/sec

Or

= (u+v) x (5/18) m/sec

  • Now you have find out the time taken by the trains to cross each other; use this formula

= (a+b)/ (u+v)

u+v is called as relative speed of trains travelling in opposite direction

 

Question 4

What is the taken by the two trains that are of length ‘a’ and ‘b’ respectively and travelling in the same direction or parallel to each other at a speed of ‘u’ and ‘v’ respectively to cross each other?


Explanation

  • The Question will contain two trains and its lengths as: ‘a’ of the first train and ‘b’ of the second train.
  • The speed of the trains will also be included  as ‘u’ as the speed of the first train and ‘v’ as the speed of the second train

           If the speed is given in terms of Km/hr, always remember to convert it to m/sec which is done by             this formula

            For train 1: =u x (5/18) m/sec and

            For train 2: = v x (5/18) m/sec

           Or

           = (u+v) x (5/18) m/sec

  • Now you have find out the time taken by the trains to cross each other; use this formula

            = (a+b)/ (u-v)

            u-v is called as relative speed of trains travelling in opposite direction

 

Question 5

What is the time taken by the two trains that start at their points: A for the first train and B for the second train that travels at a speed of ‘u’ and ‘v’ respectively to reach their destination after crossing each other?


Explanation

  • The Question will contain two trains and its’ Speed as: ‘u’ of the first train and ‘v’ of the second train.
  • You have to find out the time taken by the trains to reach their destination after crossing each other. Use this formula

           (√v: √u)

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15 replies »

  1. I am good in apti. I cleared written of cognizant and L&T. But i failed to clear zensar written because of soooooo many train problems. I am sure i wont be facing any sort of problem in solving train questions from now on wards. THANKS A TON.

    Like

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