Data Sufficiency
About 7 min · Reasoning Ability · English
Time worked out from the lesson's 559 words at 150 words a minute, plus a minute for each question.
Data Sufficiency tests your ability to evaluate whether given information is enough to answer a question—without necessarily solving the problem completely. Unlike other reasoning topics where you find the answer, here you determine if an answer can be found.
Key ideas
- Sufficiency ≠ Solving: You don't need the final numerical answer. You need to know whether the answer is determinable with given data.
- Test Each Statement Independently First: Before combining statements, check if Statement I alone or Statement II alone can answer the question. This prevents overlooking simpler solutions.
- Unique Answer Requirement: Data is sufficient only if it leads to ONE definite answer. If multiple possibilities exist, the data is insufficient.
- Common Question Categories: Data sufficiency covers coding-decoding, blood relations, direction-distance, ranking, and sometimes basic arithmetic reasoning.
- Answer Option Patterns: Standard options typically are:
Watch out for
- Mistake: Solving the entire problem instead of stopping once sufficiency is established. Fix: The moment you confirm a unique answer is possible, mark sufficient and move on—save time.
- Mistake: Combining statements too early without testing each independently. Fix: Always check Statement I alone first, then Statement II alone. You might miss that one statement is independently sufficient.
- Mistake: Assuming gender from Indian names (Raj = male, Priya = female). Fix: Gender must be explicitly stated or logically deducible.
Quick reference
- Check each statement alone before combining them.
- Sufficient = exactly ONE definite answer possible.
- Never assume gender, position, or direction not explicitly given.
- Ranking formula: Top rank = Total − Bottom rank + 1.
- Time-saver: Stop solving once sufficiency is clear—don't compute the final answer.
Check yourself: 3 questions
1. Question: What is the age of Rahul? Statement I: Rahul is 5 years older than his brother Amit. Statement II: Amit's age is 20 years.
2. Question: In which direction is point Q with respect to point P? Statement I: Point P is 10 m to the west of point R. Point Q is 8 m to the north of point R. Statement II: Point S is 6 m to the south of point P. Point Q is 14 m to the north of point S.
3. Question: What is the average salary of five employees A, B, C, D, and E? Statement I: The total salary of A and B is Rs 60,000. The total salary of C, D, and E is Rs 90,000. Statement II: The average salary of A, B, and C is Rs 28,000.
This lesson is cut from the topic's note, not rewritten. Fact-checked on 21 Oct 2026: an AI-assisted check of this note against cited sources; the errors it found were corrected that day. Some errors may remain. The questions are from Shishya's validated question bank.
Read the full noteFlashcards for this topic
Saves this lesson and its 3 questions in this browser on this phone. No sign-in; nothing about you is saved or sent. A saved copy is not updated until you save it again. Parts that load from the server when you use them (the AI tutor, adaptive practice, sign-in) still need a connection.