Enough information means one definite answer.
Data Sufficiency: do you have enough information?
An original website mini lesson · Learning On My Own
The idea
Data Sufficiency asks whether the information is enough to answer the question. For a yes-or-no question, a definite no is just as sufficient as a definite yes.
Test statement 1 alone. Then forget statement 1 and test statement 2 alone. Only combine them if neither works by itself.
Is the integer n even?
Statement 1: n is divisible by 3.
Statement 2: n is divisible by 2.
- 1 alone: n could be 3 (odd) or 6 (even). Not sufficient.
- 2 alone: Every integer divisible by 2 is even. Sufficient.
Conclusion: Statement 2 alone is sufficient; statement 1 alone is not.
A useful trap to avoid
You do not need to find n. Statement 2 allows many values—2, 4, 6, and more—but they all give the same answer to “Is n even?”
Your turn
Is integer n even?
1: n = 2k + 1 for an integer k.
2: n > 10.
See the answer and reason
Statement 1 alone is sufficient: 2k + 1 is always odd, so the answer is definitely no. Statement 2 alone is not sufficient: 11 is odd and 12 is even. Conclusion: 1 alone is sufficient; 2 alone is not.
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