GMAT Data Sufficiency

Author: Brian Galvin

Size of File: 14 MB

Number Of Pages: 266

Language: English

Category : GMAT

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GMAT Data Sufficiency Notes Download Link

Contents

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 xx?

(1) x2=16x^2 = 16

(2) ∣x∣=4|x| = 4

Step-by-step Solution

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

    • Possible values: x=4x = 4 or x=−4x = -4.
    • Since there are two possible values, NOT sufficient. → Eliminate A and D.
  • Statement (2) Alone: ∣x∣=4|x| = 4

    • Possible values: x=4x = 4 or x=−4x = -4.
    • Again, not a unique valueNOT sufficient. → Eliminate B.
  • Combining Both Statements:

    • Both give the same information: xx is either 44 or −4-4.
    • 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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