Data Interpretation
Why This Chapter Matters
DI is the highest-weightage topic in Banking exams — 15-20 marks in every paper. The key skill is speed and accuracy in reading tables, bar graphs, pie charts, and line graphs. Practice reading and calculating quickly.
Types of DI
1. Tabular DI
Data in rows and columns. Read carefully which row and column the question asks about.
Common questions: percentage, ratio, difference, increase/decrease, average.
2. Bar Graph
Compare values across categories. Read the scale carefully.
Common questions: which has highest/lowest, % increase from one year to next, ratio between two bars.
3. Pie Chart
Shows parts of a whole as % or degrees.
Total = 100% or 360 degrees.
Value = (percentage/100) x total value.
Common questions: value of a sector, ratio between two sectors, % more than another.
4. Line Graph
Shows trends over time. Good for identifying increase/decrease.
Rate of change = change in value / change in time.
5. Mixed Graph
Two types of graphs together (bar + line). Read both carefully.
Key Calculation Techniques
Percentage Calculation Shortcuts
To find x% of y: if x=10%, divide y by 10. If x=5%, divide by 20. If x=25%, divide by 4.
Build up: 17.5% = 10% + 5% + 2.5% = y/10 + y/20 + y/40.
Ratio Comparison
To compare a/b and c/d: cross multiply. If ad > bc: a/b > c/d.
Approximation
In DI, always look if you can approximate. If answer choices are far apart, rough calculation suffices.
Practice Strategy
Step 1: Read the question carefully BEFORE looking at data.
Step 2: Identify which part of the data is needed.
Step 3: Calculate ONLY what is needed (don't calculate everything).
Step 4: Use approximation when answer choices allow it.
Step 5: Eliminate wrong options quickly.
Sample DI Questions
Given table: Sales (units) for 5 companies A,B,C,D,E in 2021 and 2022.
A: 500, 600 | B: 400, 350 | C: 300, 450 | D: 600, 720 | E: 200, 300
Q1: Which company had highest % growth from 2021 to 2022?
A: 20% | B: -12.5% | C: 50% | D: 20% | E: 50%
C and E both 50% — check exact: C: 150/300=50%, E: 100/200=50%. Both same. (check question — usually there's a clear winner).
Q2: What is the ratio of total 2021 to total 2022 sales?
2021 total = 2000. 2022 total = 2420. Ratio = 2000:2420 = 100:121.
Q3: Average sales of all companies in 2022?
2420/5 = 484 units.
Previous Year Questions (Pattern)
SBI PO 2023 DI: Table with income/expenditure for 5 years. Questions on savings, % savings, year with highest growth.
IBPS Clerk 2022 DI: Pie chart of expenses. Questions on value of each sector, ratio between sectors.