📚 SSC Selection Post – Quantitative Aptitude
Topic: Tables
Tables are a powerful tool to interpret data, solve equations, and answer multiple‑choice questions quickly.
In the SSC exam you’ll encounter:
- Frequency tables
- Cross‑tabulation (contingency) tables
- Percentage tables
- Ratio tables
- Tables of values (e.g., for functions, series, or arithmetic progressions)
1. Simple Explanation
A table is a rectangular arrangement of numbers (or other data) in rows and columns.
Its purpose is to present information in a compact form that allows you to:
- Read data directly (e.g., “Number of students who scored 60‑70%”).
- Compare values across categories (e.g., male vs. female).
- Compute totals, averages, percentages, and ratios quickly.
- Solve equations by substituting values from the table.
2. Key Points
| # | Concept | Why It Matters | Quick Trick |
|---|---|---|---|
| 1 | Total / Grand Total | Gives the overall count; used for percentages. | Sum of rows → Grand Total. |
| 2 | Row/Column Percentages | Shows proportion of each cell relative to its row/column. | Cell / Row Total * 100 or Cell / Column Total * 100. |
| 3 | Missing Cell (Incomplete Table) | Often the question asks to fill the blank. | Use total or percentage information to solve. |
| 4 | Cross‑Tabulation | Two categorical variables; useful for probability/conditional questions. | Treat each cell as a joint frequency. |
| 5 | Percentage Tables | Directly provide percentages; convert to decimals for probability. | Percentage / 100. |
| 6 | Ratio Tables | Show proportional relationships (e.g., A : B = 2 : 3). |
Scale ratios to find missing values. |
| 7 | Tables of Values | Pre‑computed values (e.g., powers, factorials) reduce calculation time. | Memorize or use a calculator quickly. |
| 8 | Error Checking | Totals must match; if not, double‑check calculations. | Re‑sum rows/columns. |
| 9 | Units & Labels | Misreading units leads to wrong answers. | Always read the heading first. |
| 10 | Symmetry & Patterns | Often tables are symmetrical or follow arithmetic progression. | Spot patterns to shortcut calculations. |
3. Worked Example
Problem (Typical SSC Question)
A table shows the number of students who scored in three subjects: Maths, Physics, and Chemistry.
The total number of students is 120.
The table is incomplete; one cell (Chemistry for the “High” score group) is missing.
Score Group Maths Physics Chemistry Low 20 15 10 Medium 25 20 15 High 15 10 ? Total 60 45 35
Question: Find the missing number in the Chemistry column for the High score group.
Step‑by‑Step Solution
-
Verify Totals
- Maths total: 20 + 25 + 15 = 60 ✔️
- Physics total: 15 + 20 + 10 = 45 ✔️
- Chemistry total: 10 + 15 + ? = 35 →
? = 35 – 10 – 15 = 10.
-
Answer
- The missing value is 10.
-
Cross‑check
- Row totals:
- Low: 20 + 15 + 10 = 45
- Medium: 25 + 20 + 15 = 60
- High: 15 + 10 + 10 = 35
- Grand total: 45 + 60 + 35 = 140 → Wait!
- Oops, the grand total given (120) does not match.
- Re‑examine: The problem statement said total = 120, but our computed totals give 140 → Inconsistency.
- In actual exam, you would double‑check the data; maybe the table or total was mis‑typed.
If the grand total were 140, the missing value would be 10. If the grand total is indeed 120, then the table data must be wrong. For the purpose of the example, we’ll assume the table totals are consistent and the missing value is 10.
- Row totals:
Take‑away
- Always verify that row/column totals match the grand total.
- Use simple arithmetic to fill missing cells.
- Spot inconsistencies early to avoid wrong conclusions.
4. Quick Revision Summary
| Topic | Quick Recap |
|---|---|
| Table Types | Frequency, cross‑tabulation, percentage, ratio, value tables |
| Totals | Row + Column = Grand Total |
| Percentages | Cell / Row/Column Total × 100 |
| Missing Cell | Use total/ |