Tuesday, 4 April 2017

How to Solve Problems on Trains Easily Using Proportionality for IBPS PO Exam

Problems on trains are asked in IBPS PO Exam and can be very confusing. Read on to for smart methods to solve these questions.
Problems on trains

Problems on trains have always made their way in most competitive exams. Questions on this topic range from finding the speed of the train, distance between two trains or time taken by the two trains to cross each other. Don't let these problems bother you anymore but tackle them with ease in IBPS PO Exam. 

So here is the 5th smart method in this series that will help you solve questions in 5- 10 seconds that would otherwise take 30- 45 seconds.
Problems on trains

Problems on Trains

Problems on trains are of many kinds and can often be very daunting. Such questions need you to take into consideration directions, the length of the train, length of the station along with the speed of the train.It can be very daunting to dabble between all this and with this is the additional responsibility of remembering the list of formulas, when time is not your best friend is definitely not easy.


List of Formulas to Solve Problems on Train


1. If two trains are moving in opposite directions at v1 m/s and v2 m/s, then their relative speed
Problems on trains
2. Assume two trains of length x mts and y mts are moving in opposite directions at v1 m/s and v2 m/s, then the time taken by the trains to cross each other
Problems on trains

3. Assume two trains of length x mts and y mts are moving in the same direction at v1 m/s and v2 m/s where v1> v2, Then the time taken by the faster train to cross the slower train 
Problems on trains

Example of a Problem on Trains

A train of length 120 m long crosses a pole in 3 seconds. How long will it take to cross a railway platform of length 240 m?
1) 4.5 seconds      2) 3.5 seconds      3) 5 seconds      4) 9 seconds      5) None of these

Conventional Method to Solve Problems on Trains

Now let me guess what you did- you scrolled back to the question and went through the list of formulas to identify the formula that would solve your problem. Then you’ll got hold of the nearest notebook and pen and wrote the following steps-

Step 1:
Speed of  the Train= Length of Train/ Time taken to cross the Pole

Step 2:
Speed of the Train= 120/3= 40m/ sec

Step 3:
Time taken to cross the Platform= (Length of Train+ Length of Platform)/ Speed of the Train

Step 4:
Time taken to cross the Platform= (120+ 240)/ 40= 360/ 40= 9 sec
4 steps, 30 seconds and remembering a host of formulas! Not advisable when you are racing against time.


Smart Method to Solve Problems on Trains 

You can definitely do much better than that! A smart way that involves- 2 steps, 10 seconds and no formulas!

Step 1:
Time taken by the train to cover 120m= 3 sec, then time taken to cross (120+ 240)m?
Proportionality Equations come to our rescue here, an equation of proportionality is written in the form a:b :: c:d when the two ratios are equal and then solved by cross multiplication. 

Step 2:
(120/3):3 :: 360:x
X= 9 sec
Since Time and Distance are directly proportional to each other.
Simple and super quick! 


Problems on trains


Time to use this smart method to solve more such questions:

Question 1: A train of length 80 m long crosses a pole in 4 seconds. How long will it take to
cross a railway platform of length 120 m?
1) 12 seconds      2) 10 seconds      3) 15 seconds      4) 9 seconds      5) None of these

Question 2: A train of length 100 m long crosses a pole in 10 seconds. How long will it take
to cross a railway platform of length 64 m?

1) 14.5 seconds      2) 16.4 seconds      3) 15 seconds      4) 9.2 seconds      5) None of these

Don't forget to leave your answer in the comments below and tell us how many seconds you spend on these questions!

Watch this space for more smart methods.

Problems on trains



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