Data Interpretation

Why This Chapter Matters

Data Interpretation (DI) carries 10-15 marks in SSC CGL Tier 2 and 5-8 marks in Tier 1. Speed and accuracy in reading charts, tables, pie charts, and bar graphs determine your rank.

Types of DI Questions

1. Tables

Easiest form of DI. Data in rows and columns.

Read row and column headings carefully. Don't confuse rows with columns.

Calculate % change, ratio, average from table values.

2. Bar Graphs

Read bar heights carefully. Multiple bars: compare them.

% change = (new-old)/old × 100.

3. Pie Charts

Represent % of total. All slices add to 360° or 100%.

Value of a slice = (Angle/360) × Total OR (Percentage/100) × Total.

If total is not given but ratio of two items needed — use percentages directly.

4. Line Graphs

Show trends over time. Slope = rate of change.

Steepest rise/fall → maximum rate of change.

5. Mixed DI

Two graphs together — table + pie chart or bar + line. Most complex.

Key Skills

Approximation

In SSC DI, exact calculation is rarely needed. Round numbers to nearest convenient value.

Example: 4830/97 ≈ 4800/100 = 48. Saves 60 seconds.

% Calculation Shortcuts

10% of X = X/10 | 5% = X/20 | 25% = X/4 | 33.33% = X/3

For 17% of 342: 17% ≈ 10%+5%+2% = 34.2+17.1+6.84 = 58.14 ≈ 58.

Ratio Shortcuts

If two quantities are in ratio 3:5, out of total 800:

First = 3/(3+5) × 800 = 300 | Second = 500.

Solved DI Set

Table: Sales of a company (units in thousands)

|------|-----------|-----------|-------|

Q1: % increase in Total sales from 2019 to 2022?

= (280-200)/200 × 100 = 40%

Q2: In which year was Product B's share of total highest?

2020: 90/190=47.4% | 2021: 110/250=44% | 2022: 130/280=46.4% | 2023: 120/280=42.9%.

Highest: 2020 (47.4%)

Q3: Average sales of Product A over all 5 years?

(120+100+140+150+160)/5 = 670/5 = 134 thousand.

Q4: Ratio of Product A to Product B in 2021?

140:110 = 14:11.

PYQs (SSC)

SSC CGL 2023 (Pie Chart): A pie chart shows expenditure. Education=72°, Food=144°, Others=144°. If total expenditure is Rs 50,000, find education spend.

Education = (72/360)×50000 = 0.2×50000 = Rs 10,000.

SSC CHSL 2022 (Bar graph): Production in 2020=500, 2021=600. % increase?

= (600-500)/500 × 100 = 20%.

Revision Notes

DI STRATEGY:
1. Read all headings and units first (before questions)
2. Identify what each question asks (%, ratio, absolute, average)
3. Use approximation wherever possible
4. Check if total is given or calculable

KEY FORMULAS:
% change = (new-old)/old × 100
Pie chart value = (angle/360) × total = (%/100) × total
Average = sum/count
Ratio x:y out of total T → first = xT/(x+y)

APPROXIMATION TIPS:
Always check if options are far apart (large gap → rough calculation fine)
If options close → precise calculation needed
Round intermediate values to nearest 5 or 10