Analytical Ability - Data Sufficiency: Deciding Whether the Data Is Enough
What this domain tests
Data Sufficiency (DS) in TS ICET does not ask for the numerical answer; it asks whether the data supplied forces exactly one answer. Each question carries two statements, and the standard choices run: I alone sufficient; II alone sufficient; both required; either alone sufficient; both together still insufficient. Recognising which of these five is being tested saves more time than solving does.
Working rules
- Treat the two statements as independent witnesses. Judge statement I without peeking at II, then judge II as if I did not exist.
- 'Sufficient' means a unique value, not a plausible one. If an equation yields two valid values, the statement fails.
- Never import facts from outside the stem - no assuming integers, positives, or distinctness unless the question states it.
- Hidden constraints (integers, digits, number of people) can turn an apparently ambiguous statement into a sufficient one.
- Do not finish the arithmetic. Stop the moment uniqueness is settled.
Worked example
Question: Is x positive? Statement I: x² = 16. Statement II: x³ = −64. From I, x = 4 or x = −4, so I is not sufficient. From II, x = −4 uniquely, so II settles the question - the answer to the question is no - and is sufficient. Since I alone fails, the choice is 'statement II alone is sufficient'.
Traps
- Continuing to solve after sufficiency is established wastes the clock.
- Treating 'both statements together' as the safe default; the fifth option exists precisely because many pairs stay ambiguous.
- Confusing necessary data with sufficient data.
- Forgetting that a statement can be sufficient even when it contradicts the other statement.