Data Interpretation
What TANCET tests here
Data Interpretation asks you to read tables, bar and line graphs, pie charts and caselets, then compute shares, ratios, growth rates, averages and comparisons. The arithmetic is school-level; the challenge is locating the right data under time pressure and choosing an efficient approximation.
Core rules
- Read the title, units, footnotes and base year before touching the numbers.
- Pie charts: value = (angle/360) × total; percentage = angle/3.6.
- Growth rate = (new − old)/old × 100. Always divide by the earlier value.
- Distinguish percentage points from percent: a share rising from 25% to 27.5% is a 2.5 percentage-point rise but a 10% relative rise.
- For 'which is largest' questions, compare ratios approximately; do not compute every value fully.
- Weighted averages: a simple mean of subgroup percentages is wrong unless the subgroups are equal in size.
Worked example
A family's monthly budget is ₹48,000. On a pie chart, food occupies 90° and rent 72°. Food = (90/360) × 48,000 = ₹12,000; rent = (72/360) × 48,000 = ₹9,600. If food spending rises by 10% while the total budget stays at ₹48,000, food becomes ₹13,200, or 27.5% of the budget - up 2.5 percentage points from 25%, not 10 points. The 10% is a relative increase; the share change is measured in points.
Traps that cost marks
- Reading the row above or column beside the one the question names.
- Mixing thousands and lakhs, or rupees and percentages.
- Reporting a percentage-point change as a percent change.
- Averaging percentages across unequal groups.
- Using the latest year's figure when the question specifies a base year.