Understand the basics of Data Interpretation

Majority of the questions asked in the Data Interpretation Section are based on the following topics of the Arithmetic Section -

1. Ratios
2. Averages
3. Percentages

If the basics of these topics are clear, attempting DI in the exams becomes comparatively easy.

Now, let us go through the types of DI graphs/charts that you may encounter in the exams -

1. Pie Charts
2. Line Charts
3. Bar Graphs
4. Tabular Charts
5. Mixed Graphs

We shall now have a look at the types of questions that are asked under these Data Interpretation Graphs -

Consider the following data presented in the bar graph -

Percentage of Students who like different sports in two different years is provided in the following graph. Total number of Students is 1000 for both the years.

Year 2011 and Year 2012

Now the following types of questions may be asked from this data -

1. Sum or Difference based -

These are the most basic questions that may be asked in a DI set. For instance,

What was the sum of the total number of students who like Badminton and Cricket in both the years?

Now for such questions, first find the number of students who like the two sports in the two years -

2011 - Badminton = (12/100) * 1000 = 120

Cricket = (45/100) * 1000 = 450

Total = 570

2012 - Badminton = (20/100) * 1000 = 200

Cricket = (37/100) * 1000 = 370

Total = 570

Sum = 570 + 570 = 1140

2. Averages based Questions -

Average based questions are very commonly asked in the Data Interpretation sets. For instance,

What is the average number of students who like badminton, cricket and football in 2011?

Total students who like badminton, cricket and football in 2011 = (12 + 45 + 22) = 79% of 1000

Required average = 790/3

3. Ratio based question -

Another arithmetic operation based question that may be asked is Ratio based.

Now, these questions may be asked directly or in combination with the above. For instance,

What is the ratio of the students who like football and tennis in 2011 and those who like volleyball and squash in 2012?

Students who like football and tennis in 2011= (22 + 4) = 26% of 1000

Students who like volleyball and squash in 2012 = (10 + 5) = 15% of 1000

Remember for such questions, you do not need to do the entire calculation, because such numbers will eventually cancel out while calculating the ratios.

Required ratio = (26% of 1000) : (15% of 1000) = 26 : 15

4. Percentage based question -

These are yet other arithmetic problems that are usually asked in DI questions.

These problems again may be asked individually or in combination with the sum or difference based problems. For instance,

The students who like badminton and squash in 2011 is what per cent of the students who like football and swimming in 2011?

Students who like badminton and squash in 2011 = (12 + 2) = 14% of 1000

Students who like football and swimming in 2011 = (22+7) = 29% of 1000

Here again, do not calculate the entire value.

Required % = (14% of 1000) / (29% of 1000) * 100 = 1400/29%

Same data may be presented in the form of other graphs as well, however, the approach to attempt the questions would remain the same. You may find numbers in place of percentages or vice - versa, so do read the question carefully before proceeding.

Line Graph -

Year 2011 and Year 2012

Tabular Chart -

Pie Chart -

One more variety of question that may be asked in pie charts is the angle based. For instance,

What is the central angle corresponding to football and volleyball together for 2012?

Angle = (20 + 10)% * 360 = (30/100) * 360 = 108