Caselet DI
Overview
Caselet DI (Data Interpretation) presents numerical data embedded within a paragraph of text rather than in tables, charts, or graphs. You must extract the data, organize it mentally (or on rough paper), and then answer 3–5 questions based on that information. This format tests both reading comprehension and calculation skills simultaneously.
The difficulty is moderate—data relationships are straightforward, but the absence of visual aids means careless reading leads to errors. Mastering Caselet DI requires a systematic approach: read once for structure, read again for numbers, build your own mini-table, then solve.
Students who practice converting word-based data into tabular form consistently score well here. The key skill is patience—rushing through the paragraph causes missed conditions and wrong answers.
Key Concepts
- Data Extraction: The paragraph contains all numerical relationships. Identify entities (people, items, years) and their attributes (amounts, percentages, ratios).
- Implicit vs. Explicit Data: Some values are stated directly ("A has 240 apples"), others require calculation ("B has 20% more than A").
- Base Value Identification: Many caselets build all data around one anchor value. Find this base first—everything else follows.
- Percentage and Ratio Chains: Data often links through "X is 25% less than Y, Y is in ratio 3:4 with Z." Track these chains carefully.
- Total and Part Relationships: If given parts, you may need the total. If given total and some parts, find the remaining part.
- Conditional Statements: Watch for words like "remaining," "rest," "after giving," "out of which"—these signal derived quantities.
- Unit Consistency: Ensure all values are in the same unit before comparing or calculating.
Formulas / Key Facts
Percentage Increase: New Value = Original × (1 + P/100)
Percentage Decrease: New Value = Original × (1 – P/100)
Finding Original from Increased Value: Original = Increased Value / (1 + P/100)
Finding Original from Decreased Value: Original = Decreased Value / (1 – P/100)
Ratio to Actual: If A:B = 3:4 and total = 700, then A = (3/7) × 700
Successive Percentage: For two changes of a% and b%, net effect = a + b + (ab/100)
Fraction-Percentage Equivalents:
- 1/4 = 25%, 1/5 = 20%, 1/6 = 16.67%, 1/8 = 12.5%
- 2/5 = 40%, 3/4 = 75%, 5/6 = 83.33%
"More than" vs. "Of": "A is 25% more than B" means A = 1.25B. "A is 25% of B" means A = 0.25B.
Worked Examples
Example 1: Basic Caselet
Paragraph: A company has three departments—HR, Finance, and IT. HR has 120 employees. Finance has 25% more employees than HR. IT has 20% fewer employees than Finance. Find the total employees.
Solution:
- HR = 120
- Finance = 120 × 1.25 = 150
- IT = 150 × 0.80 = 120
- Total = 120 + 150 + 120 = 390 employees
Example 2: Ratio-Based Caselet
Paragraph: Three friends A, B, and C have savings in the ratio 2:3:5. C has Rs. 4000 more than A. B spends 40% of his savings. Find how much B has left.
Solution:
- Let savings be 2x, 3x, and 5x
- C – A = 5x – 2x = 3x = 4000
- So x = 4000/3 ≈ 1333.33
- B's savings = 3x = 4000
- B spends 40%, keeps 60%
- B has left = 4000 × 0.60 = Rs. 2400
Example 3: Multi-Step Caselet
Paragraph: A shop sold 600 items in three categories—Electronics, Clothing, and Books. Electronics formed 35% of total sales. Clothing sales were 2/3 of Electronics sales. The rest were Books. If profit on Electronics is 20%, Clothing is 15%, and Books is 25%, and each Electronics item costs Rs. 500, each Clothing item costs Rs. 300, and each Book costs Rs. 100, find total profit.
Solution: Step 1: Find quantities
- Electronics = 35% of 600 = 210
- Clothing = (2/3) × 210 = 140
- Books = 600 – 210 – 140 = 250
Step 2: Find revenue (Cost Price)
- Electronics CP = 210 × 500 = Rs. 105000
- Clothing CP = 140 × 300 = Rs. 42000
- Books CP = 250 × 100 = Rs. 25000
Step 3: Find profit
- Electronics profit = 20% of 105000 = Rs. 21000
- Clothing profit = 15% of 42000 = Rs. 6300
- Books profit = 25% of 25000 = Rs. 6250
- Total profit = Rs. 33550
Common Mistakes
Mistake: Applying percentage on wrong base. → Fix: "A is 20% more than B" means calculate 20% of B, not of A. Always identify which value is the base.
Mistake: Confusing "more than" with "of." → Fix: "20% more than 100" = 120. "20% of 100" = 20. Read the phrasing precisely.
Mistake: Forgetting to account for "remaining" or "rest." → Fix: When told "the rest are X," calculate: Rest = Total – Sum of stated parts.
Mistake: Not creating a rough table. → Fix: Always jot down entities in rows, attributes in columns. This prevents re-reading the paragraph repeatedly.
Mistake: Calculation errors under time pressure. → Fix: Use approximation for verification. If Finance = 25% more than 120, it should be between 120 and 180. Quick sanity checks catch errors.
Mistake: Misreading ratio direction. → Fix: "Ratio of A to B is 3:4" means A = 3 parts, B = 4 parts. Don't swap them.
Quick Reference
- Read the caselet twice: first for structure, second for numbers.
- Build a mini-table on rough paper before attempting any question.
- Identify the anchor/base value—most other data derives from it.
- "X% more than Y" → X = Y × (1 + X/100); "X% of Y" → X = Y × (X/100).
- Check units and ensure all calculations use consistent values.
- Verify answers with quick mental approximation—catch silly errors before moving on.