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# GMAT Data Sufficiency Questions Explained

by | Jul 18, 2024 | GMAT

#### Fatma Xhafa

Fatma is our Director of Operations and has been with Apex for over 3 years. With a background in computer science and business, she has the skills and expertise to manage day-to-day operations and lead the team effectively.

Data Sufficiency problems represent for many the most challenging problem type on the GMAT. They don’t have to be. Much of the reason they seem so challenging is because they are unfamiliar, rather than because they are complex.

Let’s break down how these problems work so that you can develop an intuition around their structure and bring them into the realm of the familiar.

Unlike standard math problems, Data Sufficiency questions require a unique approach because they are written “backwards”, providing a speculative proposition and asking you to evaluate it relative to a set of facts.

We’ll show you how to interpret these questions, tackle various question subtypes, and offer strategies to conquer each of them, so you can prepare for the GMAT effectively.

## Data Sufficiency Questions as Part of Data Insights

The Data Insights section of the  GMAT Exam (previously called the Focus Edition) is basically the former Integrated Reasoning section coupled with Data Sufficiency questions. It focuses on data literacy, analytics, and logical reasoning in the business world.

Data sufficiency questions were formerly part of the Quantitative section but have been moved to the Data Insights (DI) section in order to emphasize their importance not just to quantitative information, but also as a way to test logical reasoning more comprehensively. As a quick overview, the DI is broken down into:

• Data Sufficiency
• Multi-Source Reasoning
• Table Analysis
• Graphics Interpretation
• Two-Part Analysis

Now, let’s dive more deeply into the DS problems you will need to tackle on your GMAT test.

## GMAT Data Sufficiency Questions vs Math Questions

GMAT Data Sufficiency (DS) problems differ from regular math problems. In short, what you’re asked to determine is whether a problem is solvable with the data provided, but you don’t need to solve it

Instead of solving the problem, you only need to set it up, meaning that any time spent executing the problem is wasted. This will be very important in determining an efficient approach to DS.

Typical math classes in school bind together problem setup and execution, and it’s difficult to separate them because of this training. Even if you can, very often it takes more time than doing both steps together, but this is because the process is new and feels “clunky”.

By practicing the skill of differentiating between setup and execution you’ll be able to do the setup (Data Sufficiency) portion more quickly than both combined.

Meanwhile, you’ll be training a key managerial skill – learning to understand what you want to know and whether it is knowable, and delegating the execution to someone else. Keep reading to understand better using a real test example.

## Overview of the GMAT Data Sufficiency Question Structure

The structure of a GMAT Data Sufficiency question is unique. You’re presented with 1 stem question (the proposition), followed by 2 statements (the facts), providing additional information. All of the information in a single problem is consistent, meaning that if the problem is about the color of a car, and the first fact tells you that it is either blue or green, then the second fact will never lead you to the conclusion that it is any color besides blue and green.

Your task is to analyze the given facts to determine if either fact individually, or both together, or each alone is sufficient to answer the proposition.

Answer choices are standardized for DS questions, meaning once you get used to these problems you won’t need to waste time reading the answer choices:

1. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
2. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
3. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
4. EACH statement ALONE is sufficient.
5. Statements (1) and (2) TOGETHER are not sufficient.

The structure of DS questions contributed to their unfamiliarity. If you find them intimidating, one powerful technique is to mentally rephrase or reorder the information provided in a more familiar manner. Here’s a straightforward example:

Who won the race?

1. Either John or Abdullah won the race.
2. Either Abdullah or Deepti won the race.

Rephrase this into:

One friend told me that John or Abdullah won the race. Another told me that either Abdullah or Deepti won the race. Assuming they’re both telling the truth (as in all DS problems) can I figure out who won the race?

If the answer is YES, then there is sufficiency and you’ll need to figure out if you can still answer YES with either one fact or the other on its own. If the answer is NO, then the problem ends there with an answer of (E).

A common mistake test-takers make is solving the problem fully, wasting valuable time and mental energy. It doesn’t matter who won the race, just that we can figure it out. In the above example, it’s hard not to solve it, but as things grow more complex, getting caught up in the solution only serves as a distraction.

Practicing DS questions can hone your problem-solving skills, emphasizing not just how to find a solution but also understanding the components and information necessary for finding a solution. Lean into this challenge.

Data Sufficiency answers are exceptionally precise, but unreasonably wordy. As you’re getting used to DS problems, it can be helpful to use a simplified version of the answer choices. The answer choices for DS questions are fixed and memorizing them can improve your efficiency. Here they are in a more straightforward way:

1. Statement (1) is  SUFFICIENT
2. Statement (2) is SUFFICIENT
3. BOTH statements TOGETHER are SUFFICIENT
4. EACH statement ALONE is SUFFICENT
5. BOTH statements TOGETHERS are still INSUFFICIENT

Becoming familiar with the question stem and synthesizing the answer choices into simpler, more manageable options will make them easier to remember.

### The Decision Tree for Data Sufficiency Problems

Another, easier way to visualize the DS answers is through the decision tree below. By understanding the logical implications of each step in the evaluation process, you can easily eliminate other answer choices and direct your attention to the next step in the problem.

With practice, this decision tree will become second nature. Don’t worry about memorizing it, the practice in the coming weeks will do that for you automatically.

## The Two Types of GMAT Data Sufficiency Questions

GMAT Data Sufficiency (DS) questions come in various forms, each designed to assess different aspects of your problem-solving skills and logical reasoning.

Understanding the categories of questions you may encounter is key to solving these problems with minimum effort. An effective GMAT study plan can be beneficial in recognizing common patterns, but only if you categorize the problems in the first place.

Here are the 2 common types of GMAT DS questions:

1. Value Questions: In this question type, you need to find a unique numerical value for the given unknown. Key phrases always include question words, such as “How much…..”, “How many…..”, or “What is the value of x?”
2. Yes/No Questions: These questions require you to determine whether it is possible to derive a single, definitive answer to the proposition question asked. The information provided must lead you to a definite “yes” or “no” conclusion. These can be tricky, because a “No” is Sufficient, only “I don’t know” or “I can’t tell” would qualify as Insufficient.

Let’s move on to examples and step-by-step solutions that illustrate how to handle these different DS question types.

## Examples of DS Question Types With Their Solutions

### Example 1: Value Question

Question Stem: What is the value of the positive integer ‘n’?

1. n is a multiple of 3
2. n is a multiple of 5

Solution:

• Evaluate Statement (1) alone: If ‘n’ is a multiple of 3, it could be 3, 6, 9, etc. – insufficient as there is more than one possibility.
• Evaluate Statement (2) alone: If ‘n’ is a multiple of 5, it could be 5, 10, 15, etc. – insufficient for the same reason.
• Combine Statements (1) and (2): If ‘n’ is a multiple of both 3 and 5, the lowest common multiple is 15. However, n could also be 30, 45, etc. – insufficient as it still doesn’t provide a unique value.

### Example 2: Yes/No Question

Question Stem: Is the integer k odd?

1. k2 – 1 is an even number
2. k + 2 is an odd number

Solution:

• Evaluate Statement (1) alone: If ( k2 – 1 ) is even, then ( k^2 ) is odd, which is ONLY possible for an odd integer since the square of an even is also even. Hence, k must be odd – Sufficient. The answer will be either (A) – 1) ALONE or possibly (D) EACH ALONE.
• Evaluate Statement (2) in isolation to determine if it is also Sufficient.  If k+2 is an odd number, then k will also be odd (being 2 away), so the answer is also “Yes” making 2) also Sufficient on its own.

## Data Sufficiency Questions Explained by an Apex GMAT Tutor

Data Sufficiency Problems On The GMAT | GMAT TIPS

## Tips for Eliminating Answer Choices

Using logic and a methodical approach means searching for patterns in the questions and their structural cues, using logical reasoning and algebraic manipulation to simplify information, and thinking about the characteristics of numbers (e.g., even/odd properties, factors, multiples) to reach a conclusive answer.

Understanding the various categories of questions and the type of logic each requires will streamline your problem-solving process. For example, answering “value” questions may lean on your algebra skills, while “yes/no” questions could tap into your ability to leverage number properties and logic.

Moreover, the unique answer choice structure of GMAT DS questions aids in an efficient elimination process. Here’s a concise method:

1. Assess Statement (1) Alone: If it’s sufficient, eliminate choices (B), (C), and (E). If not, eliminate choices (A) and (D).
2. Assess Statement (2) Alone: If it’s sufficient, eliminate choice (C). If Statement (1) was sufficient too, the answer is (D); otherwise, the answer is (B).
3. Assess Both Statements Together: If they’re sufficient together but weren’t on their own, choose (C). If they’re still not sufficient, the correct answer is (E).

Using this elimination process saves time and prevents common mistakes by methodically considering each answer’s implications.

Remember, DS questions aren’t just about finding the correct answer—they test your ability to determine when you have enough information to make a decision, it’s a key business management skill.

## Summarizing Common Mistakes on GMAT Data Sufficiency Questions

### Actually Solving the Question

This is the number 1 mistake most test-takers make with Data Sufficiency problems. It’s important to remember that they’re not meant to be solved. Over-calculating wastes time and can be a drag on your overall performance.

Instead, focus on setting up the problem to determine if the given statements are sufficient. This approach saves valuable time, giving you extra minutes to tackle other questions on the Data Insights section.

### Rushing

This is another common mistake that almost every new GMAT test taker makes at one point or another. Spend enough time reading through the question in order to come up with a solution that you can be confident in, without over-allocating time to the question once you’re in safe waters.

Rushing through can be damaging to your performance because you will likely miss out on essential details. When rushing leads to a wrong answer, it would be better to just guess. Give yourself the time you need to process and apply the correct methodology. If you’re still short on time, you can work on speeding up the right process once it’s mastered.

### Not Understanding How the Facts and Proposition Work

Many test-takers overlook that the only relevant facts are in the two statements given in the question. Many wrongly assume that the proposition represents a fact, or allow information from one fact to bleed into the other.

Be sure to use only the information provided and not allow your perceptions to introduce information that isn’t explicitly stated in the facts, without assuming anything else.

## Master GMAT Data Sufficiency Questions with an Expert Tutor

Mastering GMAT Data Sufficiency (GMAT DS) is crucial for any aspiring MBA student. This unique type of question requires a methodical and systematic approach that an expert tutor can help you develop.

One-on-one sessions early on in the process can help make sense of DS questions and introduce a framework and methodology that can save you a lot of time and aggravation in the long run.

A qualified tutor can also help avoid common mistakes, such as misinterpreting what a question asks or confusing a definite answer with a probable one. With a variety of advanced techniques and relevant practice questions, a tutor can ensure that you’ll be prepared to face every challenging question the GMAT can throw your way.

Not sure if your GMAT self-prep is enough? Talk to our team for a custom prep plan.

### Is Data Sufficiency Still a Part of the GMAT?

Absolutely, despite being removed from the Quantitative section, Data Sufficiency is a crucial part of the GMAT Data Insights section. It challenges you to determine if provided data is enough to answer a question, rather than solving for a specific answer.

### How Can I Improve My Data Sufficiency Score for the GMAT?

To improve Data Sufficiency on the GMAT, focus on understanding the underlying logic of the questions and how they’re structured to cue incorrect responses. Practice identifying what information is necessary to evaluate a question and avoid common traps involving irrelevant data or overly complex calculations. Consistent practice with these question types and learning to recognize patterns will sharpen your skills.

### Does GMAT Focus Have Data Sufficiency?

Yes, GMAT Focus does include Data Sufficiency questions.

### What Is the Format of GMAT Data Sufficiency Questions?

GMAT Data Sufficiency questions are propositions followed by 2 factual statements. Your task is to decide if the factual statements provided, either separately or together, offer enough information to answer the proposition definitively. It’s all about efficient decision-making and critical analysis, not crunching numbers.