[Data Interpretation-2] Calculating Percentage Growth/Increase/Decrease

In this article you will learn how to calculate Percentage Growth/Increase/Decrease in Data Interpretation Questions. Here I will explain how to use concept of Multiplying Factor for solving Percentage Growth, Increase/Decrease questions quickly. Before moving further first visit the first part of the DI.  [Data Interpretation - 1] How to Calculate Division of two numbers quickly?

Let us take few examples:

Example: XYZ motors limited sold 7000 Scooters in year 2012. If sale of scooter is increases by 10% in year 2013. Calculate no of scooters sold in 2013.

Solution:  Increase in scooter sale = 10% ===è M.F. = 1.1 

Final Value = Initial Value * M.F.

Scooter sales in 2013 = M.F. X 7000 = 1.1 X 7000 = 7700.

Let us understand how to use Multiplying Factor  while solving DI questions.

Example: The below Graph represents Bajaj Auto’s sales volume in different segment from year 2010 to 2013.

Question: What is percentage growth in sales volume of scooter in year 2011 w.r.t. 2010.

            a) 9%            b) 10%               c) 15%                  d) 20% 

Solution: 

Normal Procedure:      No. of Scooter Sold in 2010 = 7000

                                       No. of Scooter Sold in 2011 = 7700

% Increase = [(No. of units sold in 2011 - No. of units sold in 2010) / No. of units sold in 2010] * 100

                  

                  = [( 7700 – 7000 ) / 7000] * 100 = [700/7000] * 100 = 10 %.

Using Multiplying Factor Method:

Final Value = Initial Value * M.F.

M.F. = Final Value / Initial Value 

Note: If final Value and initial Values are given you can calculate Multiplying Factor by dividing Final Value and Initial Value. Once you Got Multiplying Factor you can easily tell % increase or % Decrease.

Let us solve above problem using multiplying factor.

M.F. = Final Value/ Initial Value = 7700 / 7000 = 1.1

If Multiplying Factor = 1.1 ==è 10% increase.         ( 1.1-1=0.1*100 = 10 )

(You can do it mentally no need to raise your pen).

Initially it may appear to you that your normal method is also very fast while solving above questions. So, for showing the effectiveness of Multiplying Factor method let us solve another question.

Question: What is percentage change in sales volume of motorcycle in year 2011 w.r.t. 2010.

                        

                      a)    37% Decrease B) 36% Increase c) 31% Decrease  d) 41% Decrease

Solution: Using Multiplying Factor Method:

Final Value = 5570

Initial Value = 8820

Mutiplying Factor = Final Value / Initial Value

                               = 5570 / 8820

                               = 557 / 882

Multiplying Factor = 557/882 = 569/900 = 0.6322

% Decrease = (1-0.6322) * 100 = 36.78 %  

Hence option A] is correct.

Note: Remember That,

% Increase = (M.F. – 1) * 100

% Decrease = (1- M.F.) * 100

Multiplying Factor is a very useful concept while solving percentages, DI, Profit/Loss, CI and SI. I suggest you understand Multiplying Factor well,if you do understand M.F. you can solve all Profit/loss , CI/SI problems without any formula. 

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