Data Interpretation
Data Interpretation
Data Interpretation asks you to extract, compare and combine numbers from tables, bar and line graphs, pie charts and caselets. In KMAT this domain usually sits inside the quantitative area: the arithmetic is simple, but the volume of data and the need to choose the right comparison create time pressure.
Core rules and concepts
- Read the title, units, footnotes and base year before calculating. A table labelled in lakh crore is not in rupees.
- Percentage change = (new - old)/old × 100. The old value is always the denominator.
- In a pie chart, sector angle/360 = share of total; 1% corresponds to 3.6 degrees.
- Compare ratios by cross-multiplication rather than converting every value to a decimal.
- A weighted average is total value divided by total quantity, not the average of the individual averages.
- When options are far apart, approximate aggressively and check only the leading digits.
Worked example
A pie chart shows a company's expenditure of ₹720 lakh. The production sector is 120°. Production expenditure = (120/360) × 720 = ₹240 lakh. If production spending rises by 25% while total expenditure stays at ₹720 lakh, the new production value is ₹300 lakh, and its new angle is (300/720) × 360 = 150°.
Traps that cost marks
The most common error is using the new value as the base for percentage change. Another is confusing percentage points with percent: a share moving from 20% to 25% rises by 5 percentage points but by 25%. Pie-chart labels may sum to 99% or 101% because of rounding; do not force them to 100. In cumulative graphs, subtract adjacent values to recover the per-period figure. Finally, never average percentages without weighting them by their bases.