Data Interpretation: Tables and Missing Data
Data Interpretation: Tables and Missing Data
A table DI set gives rows and columns of numbers and asks four kinds of question: a percentage or ratio, a growth rate, an average, and (in missing-data sets) values you must first rebuild from the clues. Read the units and the totals before touching any question.
1. Working Rules
| Question asks | Do this |
|---|---|
| A is what % of B | (A/B) × 100 |
| A is what % more than B | ((A − B)/B) × 100; the base is the value after "than" |
| Growth from year 1 to year 2 | ((new − old)/old) × 100 |
| Ratio of two totals | Add each column first, then simplify |
| Average over n years | Column total ÷ n |
| Missing data | Use the given totals or percentages to fill every blank before answering |
Approximate fractions: 1/6 ≈ 16.67%, 1/7 ≈ 14.29%, 1/8 = 12.5%, 1/9 ≈ 11.11%, 1/12 ≈ 8.33%
Highest percentage growth is not always the highest absolute growth: always divide by the old value
✗ Science grew by 30 in both 2022 and 2023, so the growth rates are equal | ✓ 30/120 = 25% but 30/150 = 20%; the base differs
✗ A is 25% more than B, so B is 25% less than A | ✓ B is 20% less than A (25/125)
हिंदी नोट: तालिका वाले प्रश्नों में पहले इकाई और कुल योग देखिए। प्रतिशत वृद्धि = (नया − पुराना)/पुराना × 100। लुप्त आँकड़ों वाले प्रश्न में पहले सारे खाली स्थान भरिए, फिर उत्तर दीजिए।
Exam Pointer: Verified NTPC patterns: percentage, ratio and average questions from a marks or pass-percentage table (two January 2021 CBT-1 shifts). Year-on-year growth and missing-data tables had no verified NTPC shift in our check and are tagged syllabus-based.
2. Data Set for Patterns 1 to 3
Students enrolled in three streams at a college:
| Year | Science | Commerce | Arts | Total |
|---|---|---|---|---|
| 2021 | 120 | 80 | 100 | 300 |
| 2022 | 150 | 90 | 110 | 350 |
| 2023 | 180 | 120 | 100 | 400 |
| 2024 | 200 | 150 | 130 | 480 |
| 2025 | 240 | 160 | 150 | 550 |
Pariksha Pattern: Every Way NTPC Asks This Topic
Pattern 1: Percentage and ratio from a table
[PYQ: NTPC CBT-1 11-Jan-2021 Shift-1 | NTPC CBT-1 4-Jan-2021 Shift-2]
EXAM LEVEL
Q. Using the enrolment table, what percentage of the 2023 students took Science?
180/400 × 100 = 45%.
Answer: 45%
EXAMATLAS LEVEL
Q. Using the enrolment table, find the ratio of total Commerce students to total Arts students over the five years, and by what percentage Science exceeded Arts in 2025.
Commerce = 80 + 90 + 120 + 150 + 160 = 600 and Arts = 100 + 110 + 100 + 130 + 150 = 590, a ratio of 60 : 59. In 2025 Science exceeds Arts by 90, which is 90/150 = 60% of Arts.
Answer: 60 : 59; 60%
Pattern 2: Growth over the previous year
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Using the enrolment table, find the percentage increase in total students from 2024 to 2025.
(550 − 480)/480 × 100 = 7/48 × 100 ≈ 14.58%.
Answer: About 14.58%
EXAMATLAS LEVEL
Q. Using the enrolment table, in which year did Science enrolment grow by the highest percentage over the previous year? Which stream had the highest single-year growth rate in the whole table?
Science: 2022 30/120 = 25%, 2023 30/150 = 20%, 2024 20/180 ≈ 11.1%, 2025 40/200 = 20%, so 2022. Commerce in 2023 grew 30/90 ≈ 33.3%, and Arts' best was 30/100 = 30% in 2024; the highest is Commerce in 2023.
Answer: 2022; Commerce in 2023 (about 33.3%)
Pattern 3: Averages and comparisons with the average
[PYQ: NTPC CBT-1 11-Jan-2021 Shift-1]
EXAM LEVEL
Q. Using the enrolment table, find the average number of Arts students per year.
590/5 = 118.
Answer: 118
EXAMATLAS LEVEL
Q. Using the enrolment table, in how many years was Commerce enrolment above its five-year average? In which year was Science's share of the total highest?
The Commerce average is 600/5 = 120; only 2024 (150) and 2025 (160) are above it (2023 equals it). Science shares: 40%, about 42.9%, 45%, about 41.7%, about 43.6%, so 2023 is highest.
Answer: 2 years; 2023
Pattern 4: Missing-data tables
[Pattern: syllabus-based, PYQ-style]
Pens and pencils sold by three shops (some cells missing):
| Shop | Pens | Pencils | Total | Pens as % of total |
|---|---|---|---|---|
| P | 240 | ? | 400 | ? |
| Q | ? | 180 | ? | 40% |
| R | 300 | ? | ? | 60% |
EXAM LEVEL
Q. Find the pencils sold by shop P and the pens' percentage for P.
Pencils = 400 − 240 = 160. Pens % = 240/400 = 60%.
Answer: 160; 60%
EXAMATLAS LEVEL
Q. Find the totals for shops Q and R, and the total number of pencils sold by all three shops.
For Q, pencils are 60% of the total, so the total = 180/0.6 = 300 and pens = 120. For R, 300 pens are 60%, so the total = 500 and pencils = 200. Total pencils = 160 + 180 + 200 = 540.
Answer: Q 300, R 500; 540 pencils
60-Second Revision
- Read units and totals first.
- "More than B" uses B as the base.
- Growth % divides by the old value, so equal jumps can mean different rates.
- In missing-data sets, fill every blank before answering.