GMAT: Mastering Data Sufficiency

Have you ever heard of Data Sufficiency on the GMAT? It’s a specific type of question commonly used in consulting recruitment processes and in MBA applications.

For those unfamiliar with it, these questions are not just testing your analytical skills; they also evaluate your ability to assess information strategically. It’s a different format, and at first, it might seem confusing. But with a little practice, it becomes much easier and more intuitive.

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Here’s a practical guide with examples and tips on how to approach these questions, what to do, and what to avoid.

How Does Data Sufficiency Work?

Each question presents:

• A main question.

• Two numbered statements (1) and (2).

Your task is to decide whether the information provided in each statement (or both together) is sufficient to answer the question. You’re not supposed to solve the problem entirely—just determine if it can be solved.

The statement:

It’s a question followed by two statements, labeled as (1) and (2). You must determine if the information provided by the numbered statements is enough to answer the question asked.

You need to assess whether:

• Statement (1), ON ITS OWN, is sufficient to answer the question, but statement (2) is not.

• Statement (2), ON ITS OWN, is sufficient to answer the question, but statement (1) is not.

• BOTH statements (1) and (2) TOGETHER are sufficient to answer the question, but NEITHER of them, ON ITS OWN, is.

• EACH statement, ON ITS OWN, is sufficient to answer the question.

• The two statements, even when considered TOGETHER, are NOT sufficient to answer the question.

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Example 1: A water service provider has an auxiliary pumping system to meet peak demand, which runs for 3 hours each day with constant power. How much water is pumped daily by this system?

(1) Today, the pumping system was turned on at 4:00 PM.

(2) By 4:30 PM, the system had pumped 3,000 m³, and by 6:00 PM, it had pumped 7,250 m³.

Step-by-step:

• Statement (1): The start time doesn’t tell us anything about consumption. Insufficient.

• Statement (2): Knowing the consumption between 4:30 and 6:00 PM, we can infer the consumption over 3 hours. Sufficient.

  
  

Answer: (b) - Statement (2), by itself, is sufficient.

Practical Tip: Always test the cases thoroughly before deciding if a statement is sufficient.

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Example 2: The figure below shows a pie chart of a company’s revenue, divided into five product categories. If the company’s total revenue is $2.4M, what is the revenue from category R?

(1) x = 76

(2) The revenues of categories P, Q, and T are three times the revenue of category R.

Step-by-step:

• Statement (1): Knowing the total revenue, the angle x tells us the revenue from category R. Sufficient.

• Statement (2): The relationship between P, Q, T, and R leaves out category S, so we can’t determine the value of R. Insufficient.

  
  

Answer: (a) - Statement (1), by itself, is sufficient.

Common Mistake: Don’t confuse useful data with sufficient data. Always check if the information directly answers the question. For example: P + Q + T = 3R is useful, but it is not sufficient.

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What to Do and What to Avoid?

What to do:

• Read the question carefully. Understand exactly what you’re being asked.

• Evaluate each statement individually before combining them.

• Simplify equations or mathematical concepts to identify dependencies between the data.

• Test with numbers. In many cases, it’s quick, easy, and helps you arrive at the answer.

What to avoid:

• Solving the problem entirely. Your job is not to find the exact answer but to determine if the answer can be found.

• Assuming that generic numbers or specific cases apply to all situations. Test different scenarios!

Other Tips:

• "Not sufficient" and "we don’t know" are different things. Be careful with definitions.

• Watch out for words like "always," "all," and so on. Might be a tricky question.

The Data Sufficiency format is more than just a challenge on the GMAT—it’s a mental workout for situations where we need to make quick, strategic decisions with limited information. With practice and attention, these questions become not only easier but even fun!

If you’d like to discuss strategic consulting or learn more about our recruitment process, contact us at talents@insignia.partners.