Data Sufficiency

Definition

Data Sufficiency is to check and test the given set of information, whether it is enough to answer a question or not.¹

The GMAT really isn’t a math test. These tests are actually trying to test us on our executive reasoning skills “ that is, how well we make decisions and prioritize when faced with too many things to do in too short a length of time.

Data Sufficiency questions test our ability to (quickly) analyze a collective set of data and figure out which pieces are needed to do the job. Imagine your boss dumping a bunch of stuff on you and saying, Hey, our client wants to know whether they should raise the price on this product. Can you answer that question from this data? If so, which pieces do we need to prove the case?

We do, of course, have to do some math “ and sometimes that math is quite annoying. We usually don’t, however, have to do as much as is necessary on the more normal quant questions (PS).⁷

Who

Even if your in high school now or planning to go to college, I would suggest studying data sufficiency. As stated below: “Data Sufficiency questions test our ability to (quickly) analyze a collective set of data and figure out which pieces are needed to do the job.” The ability to do this is used in every job you may have.

If you’re planning to apply to a business school for an MBA degree, you’re likely to take the GMAT. If you’re pursuing an MS degree, e.g., mathematics, physics, chemistry, you’re likely to take the GRE. Data sufficiency is used on the GMAT and GRE to see how you’d handle a challenging problem, whether a unique problem or not.

What

Data Sufficiency questions test our ability to (quickly) analyze a collective set of data and figure out which pieces are needed to do the job.⁷

GMAT

The test is required for admission to most business schools.⁵

In general, the GMAT suits those who have strong quantitative and analytical skills, who also excel at interpreting data presented in charts, tables, and text to solve complex problems.⁵

GRE

The test is required for admission to most graduate schools and a growing number of business schools.⁵

The GRE math section tends to be more straightforward and, unlike the GMAT, includes a calculator for all quantitative problems.⁵

Why

Business schools want critical thinkers, creative problem-solvers, good decision makers—people who can take core quant knowledge and solve a unique GMAT Quant question using that information. Given this, GMAT question writers need to make the Quant section [e.g., data sufficiency] of the exam in such a way that it assesses not just who has the requisite quant knowledge, but also who has these more important skills and abilities.³

See Theoretical Knowledge Vs Practical Application.

How

Understanding Solution Selections

For solving data sufficiency questions you need to first understand the question and based on that, selection should be made. The questions will be asked with certain information with two statements labeled I and II. You need to analyze whether the information given in the label I and II is adequate to come to the solution or not. You should use all the data given in the statements along with your mathematics skill and well-known facts (such as sun rises in the east or the meaning of niece).⁴

Choices

A. Data in statement 1 is sufficient alone to determine the answer.
B. Data in statement 2 is sufficient alone to determine the answer.
C. Data in either of the statements is sufficient to determine the answer.
D. Data provided in both the statements together are not sufficient to determine the answer.
E. Data in both statements are required to determine the answer.

Sample Problems

Question 1 : Question – Who is the tallest among the brothers A, B, C, D ?

Statement 1 : C is shorter than only B
Statement 2 : D is taller than only A

I) Statement 1 alone is sufficient
II) Statement 2 alone is sufficient
III) Both statement 1 and statement 2 together are sufficient
IV) Both statement 1 and statement 2 even together are not sufficient

Solution : If we consider statement 1 only, we can safely conclude that B is the tallest of all.
If we consider statement 2 only, we can safely conclude that A is the shortest of all.
Therefore, statement 1 alone is sufficient to answer the question.

Question 2 : What is the value of ‘x’

Statement 1 : x² + x – 6 = 0
Statement 2 : x ≥ 0

Solution : If we consider statement 1 alone, we have the following.

x² + x – 6 = 0
=> x² + 3x – 2x – 6 = 0
=> (x + 3) (x – 2) = 0
=> x = -3, 2
If we consider statement 2 alone, we have x ≥ 0
Combining the two statements, we can safely say that x = 2
Therefore, both statement 1 and statement 2 together are sufficient but neither alone is sufficient.

Many of the References and Additional Reading websites and Videos will assist you with data sufficiency.

As some professors say: “It is intuitively obvious to even the most casual observer.“

References

¹ “Data Sufficiency Reasoning Key Concepts, Solved Examples Here!”. 2020. Testbook Learn. https://testbook.com/learn/data-sufficiency-reasoning/.

² Arora, Nishant. “Data Sufficiency – GeeksforGeeks”. 2016. GeeksforGeeks. https://www.geeksforgeeks.org/data-sufficiency/.

³ “GMAT Data Sufficiency—The Great Equalizer”. 2022. mba.com. https://www.mba.com/exams-and-exam-prep/gmat-exam-prep/gmat-data-sufficiency-expert-tips.

⁴ “Formula For Data Sufficiency | Prepinsta”. 2022. PREP INSTA. https://prepinsta.com/data-sufficient/formulas/.

⁵ “GMAT Vs GRE: Which Test Is Right For You?”. 2022. princetonreview.com. https://www.princetonreview.com/business/gmat-vs-gre.

⁶ “Who Should Take the GMAT?” 2022. Masters in Human Resources Degrees. http://www.masters-in-human-resources.org/faq/who-should-take-the-gmat/.

⁷ Koprince, Stacey. “How Data Sufficiency Works”. 2013. manhattanprep.com. https://www.manhattanprep.com/gmat/blog/how-data-sufficiency-works/.

Additional Reading

“7 Expert GMAT Data Sufficiency Tips + Examples • PrepScholar GMAT”. 2017. Online GMAT Prep Blog By PrepScholar. https://www.prepscholar.com/gmat/blog/gmat-data-sufficiency-tips/.

“Data Sufficiency Questions In Logical Reasoning – 20 Data Sufficiency Questions & Answers”. 2022. BYJUS. https://byjus.com/govt-exams/data-sufficiency-questions-reasoning/.

MᶜGarry, Mike. 2016. “GRE Data Interpretation Practice Questions”. Magoosh Blog — GRE® Test. https://magoosh.com/gre/gre-data-interpretation-practice/.

“Reasoning – Alpha Numeric Sequence”. 2022. tutorialspoint.com. https://www.tutorialspoint.com/reasoning/reasoning_alpha_numeric_sequence.htm.

“Should I Take The GMAT? – Abound: MBA”. 2022. Abound: MBA. https://abound.college/mba/advice/should-i-take-the-gmat/.

“Tips, Tricks & Solved Examples On Data Sufficiency For Government Exams 2022”. 2022. BYJUS. https://byjus.com/govt-exams/data-sufficiency-competitive-exams/.

Videos

700+ Data Sufficiency: Breaking Down 5 Very Difficult DS Questions

In this “700+ Data Sufficiency: Breaking Down 5 Very Difficult DS Questions” live stream, Erika John from PrepScholar GMAT walks through how to solve 5 of the hardest GMAT Data Sufficiency questions and discusses what we can learn about the most challenging Data Sufficiency questions from them.

Online Lesson: Introduction to GMAT Data Sufficiency

In “Overview of GMAT Quant”, we discuss the makeup of the GMAT Quantitative section, answering the question “How many Data Sufficiency questions are there on the GMAT?” In “Structure of Data Sufficiency questions”, we review the three components of a Data Sufficiency problem (the question stem, the statements, and the answer choices) and discuss Data Sufficiency GMAT tips related to this structure. We then delve into the answer choices with “What is Sufficiency?” by discussing what the “sufficiency” in GMAT Data Sufficiency means and looking at the two different kinds of sufficiency we see in Data Sufficiency questions.

Once we’ve covered the foundations of GMAT Data Sufficiency, we take a detour for “What’s the Point of Data Sufficiency?” to discuss how Data Sufficiency problems test skills critical to success in business school and careers in business. We then discuss “How to Approach Data Sufficiency Questions” at a broad level, walking chronologically through the steps test takers can apply on each Data Sufficiency problem and providing additional GMAT Data Sufficiency tips. Finally, we walk through more specific Data Sufficiency GMAT Strategy in “Data Sufficiency Strategies”, covering four of the most useful strategies test takers can use on GMAT Data Sufficiency problems.