Tables – Quantitative Aptitude
(NIA Recruitment – Program “Quantitative Aptitude”)
1. Simple Explanation
A table is a systematic arrangement of data in rows and columns.
In aptitude tests, tables are used to:
- Present a large amount of data in a compact form.
- Let you read off values, compare them, and infer relationships quickly.
- Check whether you can interpret information, spot patterns, and calculate derived values (percentages, ratios, growth, etc.).
Tip – Before diving into calculations, spend a few seconds to glance at the whole table. Notice the headings, units, and any “>”, “<”, “≈”, or “%” symbols that give clues.
2. Key Points
| Area | What to Look For | Why It Matters |
|---|---|---|
| Headers | Column and row titles, units of measurement, reference values | They tell you what each cell represents. |
| Alignment | Numbers are usually right‑aligned, text left‑aligned | Helps spot outliers or missing values. |
| Units | kg, %, ₹, years, m/s, etc. | Prevents unit‑confusion mistakes. |
| Missing Data | Blank cells, “—”, “NA” | Often a question is to fill these in. |
| Footnotes | “*” or “**” with explanations | Don’t ignore them – they can change calculations. |
| Totals/Grand Totals | Bottom‑right cell | Useful for cross‑checking. |
| Percentages | Cells may already be in % of a row/column | Avoid double‑counting. |
| Growth/Change | “+”, “–”, “Δ” | Indicates direction of change. |
3. Types of Tables
| Type | Typical Use | Example |
|---|---|---|
| Data Table | Raw data for immediate reading | Student marks in a class |
| Frequency Table | Counts of occurrences | Number of people in each age group |
| Contingency Table | Two categorical variables | Gender vs. exam pass/fail |
| Growth Table | Year‑by‑year increase/decrease | Population growth over decades |
| Ratio Table | Proportional relationships | Ingredient amounts in a recipe |
| Comparison Table | Side‑by‑side comparison | Performance of two products |
4. Common Question Types
- Read‑off – “What is the value in row X, column Y?”
- Comparison – “Which is greater/less: A or B?”
- Percentage/Ratio – “What percentage of X is Y?”
- Missing Value – “Fill in the blank.”
- Summation/Total – “What is the total of column C?”
- Growth/Change – “What is the rate of change from Year 1 to Year 2?”
- Ranking/Ordering – “Arrange the cities from largest to smallest population.”
- Cross‑referencing – “Which row satisfies condition A and column B?”
5. Tips & Tricks
| Situation | Trick |
|---|---|
| Large numbers | Use place value to check plausibility. |
| Percentages | Convert to fractions before calculating (e.g., 25 % → 1/4). |
| Growth | For compound growth, use the formula Final = Initial × (1 + r)^n. |
| Missing value | If a total is given, subtract the known values to find the missing one. |
| Cross‑checking | Sum row totals and column totals; they should match the grand total. |
| Units | Convert all to the same unit first (cm to m, kg to g). |
| Speed | Practice mental math for simple operations (addition, subtraction, multiplication by 5, 10). |
6. Worked Example
Scenario
A company sells two products, Alpha and Beta.
The table below shows the monthly sales (in units) for the first six months of 2024.
| Month | Alpha | Beta | Total |
|---|---|---|---|
| Jan | 120 | 80 | 200 |
| Feb | 150 | 90 | 240 |
| Mar | 140 | 70 | 210 |
| Apr | 160 | 100 | |
| May | 170 | 110 | 280 |
| Jun | 190 | 120 | 310 |
Question 1:
What was Alpha’s sales in April?
Question 2:
Which product had a higher average monthly sales?
Question 3:
What is the percentage increase in total sales from March to April?
Step‑by‑Step Solution
Q1 – Reading the table
- Find the April row.
- Look under Alpha → 160 units.
Answer: 160 units.
Q2 – Calculating average
| Product | Total Units (Jan‑Jun) | Months | Average |
|---|---|---|---|
| Alpha | 120 + 150 + 140 + 160 + 170 + 190 = 890 | 6 | 890 |