Data Interpretation section of the CAT exam comprises of charts, tables, graphs, venn diagrams and other DI formatsthat tests candidates aptitude for data analysis and interpretation. DI questions can prove to be lengthy and time consuming if candidates don't have the right approach. Therefore, Data Interpretation shortcuts and tricks can come in handy for the MBA aspirants appearing for the CAT exam. Check out these simple yet effective DI tricks and short cuts recommended by MBA toppers and experts.
Calculating (Approximating) Fractions
To calculate a fraction p/q by approximation methodaddor subtract a value to the denominator and a corresponding value to the numerator.
'What is the value of 1789/762?'
We can take the denominator value close to either 250 or 300. Let's see how it works in both the cases. We know that the answer is between 2 and 3, so for adding or subtracting values from the denominator or the numerator, we will consider a factor of 2.5.
762 is 12 above 750, so we will subtract 12 from the denominator. Keeping the factor of 2.5 in mind, we will subtract 25 from the numerator.
Our new fraction is,
(1789 – 25) / (762 – 12) = 1764 / 750 = 1764*(4/3000)= 7.056/3 = 2.35 (approx.)
Actual answer is 2.35 (approx.)
As you can see, with very little effort involved in approximation, we arrived really close to the actual answer.
762 is 38 below 800, so we will add 38 to the denominator. Keeping the factor of 2.5 in mind, we will add 95 to the numerator.
Our new fraction is,
(1789 + 95) / (762 + 38) = 1884 / 800 = 2.36 (approx.)
As you can see, even this is close to the actual answer. The previous one was closer because the magnitude of approximation done in the previous case was lesser.
How to calculate percentage change
Here’s how you can calculate percentage change quickly using a shortcut technique:
(|New Value – Old Value|/ Old value)*100
(The "|" symbols mean absolute value, so negatives become positive)
Example: A student scored 200 marks out of 300 in Term 1 and 240 marks out of 300 in Term 2. What is the percentage increase in the marks scored by the student?
To calculate the percentage increase in the marks scored by the student in term 2 compared to the term 1,follow these steps,
- Step 1:Subtract the term 1 marks (i.e. 200) from the term 2 marks (i.e. 240) and divide the result by the absolute value of the term 1 marks (i.e. 200).
- Step 2: Multiply the resulting value from step 1 by 100 and you will get the net increase in the student's marks.
(|240-200|/ 200)*100 = (40/200)*100 = 20% increase
Example: But if that student scored 240 marks out of 300 in Term 1 and 200 marks out of 300 in Term 2. What is the net decrease in the marks scored by the student?
To calculate the netdecrease in the marks scored by the student in term 2 compared to the term 1 follow these steps,
- Step 1:Subtract the term 1 marks (i.e. 200) from the term 2 marks (i.e. 240) and divide the result by the absolute value of the term 2 marks (i.e. 240).
- Step 2: Multiply the resulting value from step 1 by 100% and you will get the net decrease in the student's marks.
(|200-240|/240)*100 = (40/240)*100 = 16.6% Decrease
Change in Averages
Here’s how you can find averages or change in average questions quickly using a shortcut technique.
- Step 1: Calculate difference between old average and new average
- Step 2: Divide the difference by the sample size for average à it will give you average increase
- Step 3: Multiply the average increase by the sample size
The average of a student in 6 subjects is 20 marks. In the next subject, he secures 41 marks. What will be his new average?
New average = (old marks + new marks)/(total number of subjects) = [(6x20)+41]/(6+1) = 23
- Step 1: Take the difference between the new marks and the old average = 41 – 20 = 21
- Step 2: This is 21 marks which is spread over 7 subjects. So, the marks average will increase by 21/7 = 3
- Step 3: Hence, the average increases by => 20+3 = 23
These were just a few tricks and shortcuts that you can employ to handle Data Interpretation Questions in CAT exam. For more such tricks and tips, please visit www.jagranjosh.com.