Data Sufficiency in Reasoning
advanced26 min read
The 'is statement I / II / both / either / neither sufficient' format applied to relations, orders, directions and codes. Test each statement alone before combining, and stop as soon as the answer is uniquely fixed.
What you will be able to do
- Apply the five standard sufficiency options without solving the whole question.
- Evaluate statement I alone, then statement II alone, before ever combining them.
- Judge 'sufficient' as 'the answer is uniquely determined', not 'I found an answer'.
- Avoid the traps: assumed positive integers, assumed directions, and combining too early.
What is inside this lesson
- 1The format and the five options
- 2Alone first, then together
- 3'Sufficient' means uniquely determined
- 4The usual traps
- 5Worked examples through all five options
- 6Quick revision
- 7Practice
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The format and the five options
A question is followed by two statements, I and II. You do not give the answer to the question — you say how much of the data is needed to answer it. The five standard options:
- (a) I alone is sufficient, II alone is not.
- (b) II alone is sufficient, I alone is not.
- (c) each statement alone is sufficient.
- (d) I and II together are sufficient, but neither alone.
- (e) I and II together are still not sufficient.
The question can be about a family relation, a seating order, a direction, a rank, or a code.
The lesson itself is for members
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