Tamil Nadu Patwari / Lekhpal – Quantitative Aptitude
Topic: Caselets
Caselets – short, scenario‑based problems that require a quick application of arithmetic, algebra, or data interpretation.
They test reading comprehension, logic, and basic math skills under time pressure.
1. Simple Explanation
| What are they? | Why they matter? | Typical format |
|---|---|---|
| Small, self‑contained problems that describe a situation (e.g., “A shopkeeper bought X goods…”) | They appear in the exam under Quantitative Aptitude → Caselets. Accurate, fast solutions are essential. | Fact‑based question → Data → Question(s) → (Sometimes) multiple sub‑questions. |
Key Idea:
Extract the numerical information → Translate into an equation → Solve → Check the answer against the story.
2. Key Points & Strategies
| Strategy | Why it works | Quick Tips |
|---|---|---|
| Read the whole paragraph once | It prevents missing important details. | Highlight numbers in the margin. |
| List the data | Keeps track of variables and units. | Use a 2‑column table: Variable |
| Identify the question type | Determines the formula (e.g., percentage, ratio, rate). | Look for keywords: profit/loss, increase/decrease, average, time |
| Write down the equation first | Avoids calculation mistakes. | Keep the equation neat; use parentheses. |
| Check units | Avoids wrong answers (e.g., km/hr vs m/s). | If units don’t cancel, redo the equation. |
| Round only at the end | Keeps intermediate values exact. | Use full precision until the final answer. |
| Double‑check with a sanity test | Confirms plausibility. | Compare with simple estimates. |
| Time‑management | 1–2 minutes per caselet is adequate. | If stuck, skip and return if time permits. |
Common Traps
| Trap | How to avoid |
|---|---|
| Mis‑identifying variables | Write down each variable explicitly. |
| Using wrong formula | Match the problem statement to the correct relation. |
| Unit mismatch | Convert all quantities to a common unit before solving. |
| Forgetting to add/subtract base value | Keep the “initial” or “final” value in the equation. |
3. Worked Example
Caselet
A farmer bought 120 kg of wheat at ₹30 per kg. He sold it at a 10 % profit on the cost price.
a) What was the total revenue?
b) If he had sold the wheat at ₹35 per kg, what would have been his profit percentage?
Step‑by‑Step
| Step | Explanation | Calculation |
|---|---|---|
| 1. Extract data | Quantity = 120 kg, Cost price per kg = ₹30, Profit % = 10 % | |
| 2. Compute total cost | ( \text{Cost} = 120 \times 30 = ₹3600 ) | ₹3600 |
| 3. Compute profit | ( \text{Profit} = 10% \times 3600 = 0.10 \times 3600 = ₹360 ) | ₹360 |
| 4. Compute revenue (a) | ( \text{Revenue} = \text{Cost} + \text{Profit} = 3600 + 360 = ₹3960 ) | ₹3960 |
| 5. Compute new selling price (b) | New price per kg = ₹35 → New revenue = (120 \times 35 = ₹4200) | ₹4200 |
| 6. Compute new profit | ( \text{New profit} = 4200 - 3600 = ₹600 ) | ₹600 |
| 7. Compute new profit % | ( \text{Profit %} = \frac{600}{3600} \times 100 = 16.67% ) | 16.67 % |
Answers
| Question | Answer |
|---|---|
| a) Total revenue | ₹3960 |
| b) Profit percentage at ₹35/kg | 16.67 % |
4. Quick Revision Summary
- Read once → List data → Identify question type → Write equation → Solve → Sanity check.
- Keep units consistent (kg, Rs, km, hrs, etc.).
- Use full precision until the last step, then round as required.
- Common formulas:
- Profit/Loss : ( P = C \pm % \times C )
- Percentage change : ( \frac{\text{Change}}{\text{Original}} \times 100 )
- Average : ( \frac{\text{Sum of items}}{n} )
- Rate–Time–Distance : ( D = R \times T )
- Simple Interest : ( SI = P \times R \times T / 100 )
- Compound Interest : ( A = P(1 + r/n)^{nt} ) (rare in caselets)
- Typical words to watch: profit, loss, increase, decrease, average, ratio, total, difference.
- Time: 1–2 min per caselet; skip if stuck, return if time allows.
Practice Tip: Create your own mini‑caselets from everyday scenarios (e.g., buying/selling items, travel estimates) and solve them within a minute.
Good luck with your preparation!