Incorrect Answers In MUST BE TRUE Questions

by on September 16th, 2009

There are several types of answers that appear in Must Be True questions that are incorrect. These answers appear frequently enough that we have provided a review of the major types below. Each answer category below is designed to attract you to an incorrect answer choice, and after this brief review we will examine several GMAT questions and analyze actual instances of these types of answers.

1. Could Be True or Likely to Be True Answers

Because the criteria in the question stem requires you to find an answer choice that Must Be True, answers that only could be true or are even likely to be true are incorrect. These answers are attractive because there is nothing demonstrably wrong with them (for example, they do not contain statements that are counter to the stimulus). Regardless, like all incorrect answers these answers fail the Fact Test. Remember, you must select an answer choice that must occur based on what you have read.

This category of incorrect answer is very broad, and some of the types mentioned below will fall under this general idea but place an emphasis on a specific aspect of the answer.

2. Exaggerated Answers

Exaggerated Answers take information from the stimulus and then stretch that information to make a broader statement that is not supported by the stimulus. In that sense, this form of answer is a variation of a could be true answer since the exaggeration is possible, but not proven based on the information. Here is an example:

If the stimulus states, “Some software vendors recently implemented more rigorous licensing procedures.”

An incorrect answer would exaggerate one or more of the elements: “Most software vendors recently implemented more rigorous licensing procedures.” In this example, some is exaggerated to most. While it could be true that most software vendors made the change, the stimulus does not prove that it must be true. This type of answer is often paraphrased, creating a deadly combination where the language is similar enough to be attractive but different enough to be incorrect.

Here is another example:

If the stimulus states, “Recent advances in the field of molecular biology make it likely that many school textbooks will be rewritten.”
The exaggerated and paraphrased version would be: “Many school textbooks about molecular biology will be re-written.”

In this example, likely has been dropped, and this omission exaggerates the certainty of the change. The paraphrase also is problematic because the stimulus referenced school textbooks whereas the paraphrased answer refers to school textbooks about molecular biology.

3. “New” Information Answers

Because correct Must Be True answers must be based on information in the stimulus or the direct result of combining statements in the stimulus, be wary of answers that present so-called new information—that is, information not mentioned explicitly in the stimulus. Although these answers can be correct when they fall under the umbrella of a statement made in the stimulus, they are often incorrect. For example, if a stimulus discusses the economic policies of Japan, be careful with an answer that mentions U.S. economic policy. Look closely at the stimulus—does the information about Japanese economic policy apply to the U.S., or are the test makers trying to get you to fall for an answer that sounds logical but is not directly supported? To avoid incorrectly eliminating a New Information answer, take the following two steps:

  1. Examine the scope of the argument to make sure the “new” information does not fall within the sphere of a term or concept in the stimulus.
  2. Examine the answer to make sure it is not the consequence of combining stimulus elements.

4. The Shell Game

The GMAT makers have a variety of psychological tricks they use to entice test takers to select an answer choice. One of their favorites is one we call the Shell Game: an idea or concept is raised in the stimulus, and then a very similar idea appears in the answer choice, but the idea is changed just enough to be incorrect but still attractive. This trick is called the Shell Game because it abstractly resembles those street corner gambling games where a person hides a small object underneath one of three shells, and then scrambles them on a flat surface while a bettor tries to guess which shell the object is under (similar to three-card Monte). The object of a Shell Game is to trick the bettor into guessing incorrectly by mixing up the shells so quickly and deceptively that the bettor mistakenly selects the wrong shell. The intent of the GMAT makers is the same.

5. The Opposite Answer

As the name suggests, the Opposite Answer provides an answer that is completely opposite of the stated facts of the stimulus. Opposite Answers are very attractive to students who are reading too quickly or carelessly. Because Opposite Answers appear quite frequently in Strengthen and Weaken questions, we will discuss them in more detail when we cover those question types.

6. The Reverse Answer

Here is a simplified example of how a Reverse Answer works, using italics to indicate the reversed parts:

The stimulus might state: “Many people have some type of security system in their home.”

An incorrect answer then reverses the elements: “Some people have many types of security systems in their home.”

The Reverse Answer is attractive because it contains familiar elements from the stimulus, but the reversed statement is incorrect because it rearranges those elements to create a new, unsupported statement.


  • I would highly recommend a book for cracking GMAT CR. i.e Power score bible for Critical reasoning. I havent yet attempted GMAT but i have completed CR bible and found it so good push right from the start. I did tried myself on few questions before and was fighting with CR. After deciding at one go that i should complete and gain field right from the start it helped me a lot. I still need to improve on few things and speed is automatically improved afterwards.

    Please note i am just a subsriber of this forum not at all related with david or this just turned out to be coincidence that author is CEO of powerscore.
    Highly recommend it, if you have time constraints do few chapters that are for must true, inferance and other important types.

  • Thank you for the recommendation Indi.

    - Adam

  • With Must be true Question types are they generally inference or assumptions?

  • Hi Ravi,
    Thanks for the question. Asked Dave Killoran for his comments on your question, and this is his reply: 
    By definition, Must Be True (MBT) questions are all based on inferences. Assumptions are actually classified as a different question type. The difference between MBT questions and Assumption questions is one I discuss in the PowerScore GMAT Critical Reasoning Bible, and here is part of that discussion: 
    "Because assumptions are described as what must be true in order for the conclusion to be true, some students ask about the difference between Must Be True question answers and Assumption question answers. The difference is one that can be described as before versus after: Assumption answers contain statements that were used to make the conclusion; Must Be True answers contain statements that follow from the argument made in the stimulus. In both cases, however, there is a stringent requirement that must be met: Must Be True answers must be proven by the information in the stimulus; Assumption answers contain statements the author must believe in order for the conclusion to be valid."
    I hope that helps, and please do not hesitate to let us know if you have any other questions. Thanks!

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