GMAT Data Sufficiency

GMAT Data Sufficiency (DS) Overview

Data Sufficiency is a unique question type in the GMAT Quantitative section designed to test your ability to analyze information and determine whether given data is sufficient to answer a question. Instead of solving for an exact answer, you assess whether the provided statements are enough to find a solution.

GMAT Data Sufficiency Question Format

Each question consists of:

1. A question stem (the problem to be solved).
2. Two statements labeled (1) and (2), providing additional information.
3. Five answer choices, always the same:

Answer Choice	Meaning
A	Statement (1) alone is sufficient, but (2) is not.
B	Statement (2) alone is sufficient, but (1) is not.
C	Both statements together are sufficient, but neither alone is.
D	Each statement alone is sufficient.
E	Even both statements together are not sufficient to answer the question.

GMAT Data Sufficiency Strategy

1. Understand the Question Type

   • Is it a yes/no question? (e.g., "Is x positive?")
   • Is it a value-based question? (e.g., "What is the value of x?")

2. Evaluate Statement (1) Alone

   • Determine if it is enough to answer the question.
   • If sufficient, eliminate B, C, and E.

3. Evaluate Statement (2) Alone

   • If sufficient alone, eliminate A and C.

4. Combine the Statements (if necessary)

   • If neither alone is sufficient, check if together they answer the question.

Example GMAT Data Sufficiency Question

Question: What is the value of $x$?

(1) x2=16x^2 = 16x2=16

(2) $|x|=4$

Step-by-step Solution

• Statement (1) Alone: x2=16x^2 = 16x2=16

  • Possible values: $x=4$ or $x=-4$.
  • Since there are two possible values, NOT sufficient. → Eliminate A and D.

• Statement (2) Alone: $|x|=4$

  • Possible values: $x=4$ or $x=-4$.
  • Again, not a unique value → NOT sufficient. → Eliminate B.

• Combining Both Statements:

  • Both give the same information: $x$ is either $4$ or $-4$.
  • Still not a single unique value.
  • Insufficient.

Final Answer: E (Even both statements together are not sufficient).

GMAT Data Sufficiency Tips

✅ Don’t solve completely—just determine sufficiency.

✅ Check for hidden constraints in absolute values, inequalities, and number properties.

✅ Memorize answer choices to save time.

✅ Watch for Yes/No traps—getting both “yes” and “no” means insufficient.

✅ Think algebraically and conceptually instead of plugging in numbers.

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