How to Solve Inference Questions on the GMAT

When evaluating critical reasoning questions, you often notice multiple answer choices that all seem plausible. The GMAT testmakers are experts at creating answer choices that are plausible and could potentially be correct, given slightly different circumstances. When evaluating strengthen or weaken questions, it is best to predict an answer from the stimulus before looking at the answer choices. That way you won’t be swayed by logical but out of scope questions (plus it’s a surprise!)

For inference questions, though, you must go through the complete gamut of choices to see which one must be true. For example, just by saying that Ron is taller than his brother (let’s call him Tom), I could make a series of inferences from that statement. Most classically, Ron is taller than Tom; therefore Ron is taller than Tom. I’m repeating the statement, so it must necessarily be true. Going a little further in my analysis, I could infer that Tom is shorter than Ron. This must also be true based on the evidence.

Another equally viable inference would be “The square of Ron’s height is greater than the square of Tom’s height” or “It takes more fruit by the foot to measure Ron than Tom”. There could be any number of (increasingly silly) inferences that could be drawn based on a simple statement, and identifying which one must be correct will have to be based on perusing the answer choices and selecting the one that cannot be false. As such, inference questions are much more a process of elimination of what we know to be incorrect.

Of course, the inferences being drawn are not as cut and dry as X is taller than Y, but the same principles apply. The correct answer must always be true, regardless of any situation (i.e. whether Capricorn is under Scorpio). An answer is incorrect even if it’s only sometimes false. Incorrect answers can be right 99.9% of the time, but if it’s wrong even once, then it cannot be the right answer. Let’s look at an example:

Informed people generally assimilate information from several divergent sources before coming to an opinion. However, most popular news organizations view foreign affairs solely through the eyes of our State Department. In reporting the political crisis in foreign country B, news organizations must endeavor to find alternative sources of information.

Which of the following inferences can be drawn from the argument above?

(A) To the degree that a news source gives an account of another country that mirrors that of our State Department, that reporting is suspect.
(B) To protect their integrity, news media should avoid the influence of State Department releases in their coverage of foreign affairs.
(C) Reporting that is not influenced by the State Department is usually more accurate than are other accounts.
(D) The alternative sources of information mentioned in the passage might not share the same views as the State Department.
(E) A report cannot be seen as influenced by the State Department if it accurately depicts the events in a foreign country.

In this question, the author is contrasting how informed people get their news in general versus one specific situation: foreign affairs. Since foreign affairs are reported on by news organizations uniquely through the filter of the state department, it stands to reason that this is at odds with the initial statement of how informed people get their information. The author then concludes that news organizations should attempt to find secondary sources of information instead of relying exclusively on the state department.

Once we understand the author’s point, we can evaluate which answer choices must necessarily be true because of it. Answer choice A is somewhat difficult to follow, but it states that other news sources that give the same information as our state department should be viewed with skepticism. This isn’t what the author is saying. The author states that, regardless of the validity of the data provided by the state department information, we should strive to have corroborating sources. No matter how good one source is, it can’t do everything itself (e.g. Lebron James in Cleveland)

Answer B again seems to paint the state department in a negative light (I’m beginning to believe the author may soon mysteriously disappear). The media can report on what the state department releases, however they should also aspire to find a second and third source to support the findings provided. B is thus incorrect.

Answer choice C is tempting. It hits on the author’s theme that information would be more believable if it were not coming solely from the state department. However again the author’s point is not that the State department information is tainted per se, only that multiple sources tend to provide a more complete picture. Including the state department among the sources should increase the accuracy of the information, not decrease it.

Answer choice D is perfect. The author wants to take into consideration other sources of information, and these sources (in conjunction with the reverse vampires) will provide a more complete picture. The only way the author’s conclusion of multiple sources providing more informed information wouldn’t be true is if they all just parroted the information provided by the state department. If all the sources say the same thing, then there’s no difference. But if some sources differ, then the full picture begins to emerge. Answer choice D also doesn’t use strong language, only that the sources *may* have different information. Answer choice D is the correct answer.

Answer choice E discusses whether or not choices are influenced by the state department, again calling into question the partiality of the state department. If the events unfolding in other countries are reported on accurately, then there is no claim that the state department was involved. The reverse need not be true, though. This answer choice seems correct but doesn’t actually say anything with regards to the author’s conclusion.

In inference questions, it’s important to always consider whether an answer choice has to be true. If it always has to be true, then it’s the correct answer. If there’s one (or more) situation in which it doesn’t hold , then it cannot possibly be correct.

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Ron Awad is a GMAT instructor for Veritas Prep based in Montreal, bringing you weekly advice for success on your exam.  After graduating from McGill and receiving his MBA from Concordia, Ron started teaching GMAT prep and his Veritas Prep students have given him rave reviews ever since.

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