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What Sherlock Holmes Can Teach You About GMAT Inference Questions

“When you have eliminated the impossible, whatever remains, however improbable, must be the truth.” – Sherlock Holmes

Someone walks in front of you with a piece of toilet paper attached to his shoe; your friend walks up to you and you notice a small bandage on his face, which smells of aftershave; a smiling woman playfully rubs her leg against her conversation partner’s under the table.

All of these situations lend themselves to inferences, because we can make an educated guess as to the causes and motivations behind each scenario. You’ll have to be an expert at making similar guesses on the GMAT. That’s why you can learn some lessons from the master of inferences, Sherlock Holmes:

Every day in our every interaction with others, we unconsciously make hundreds of inferences about all sorts of observations – the meaning of a friend’s brief text message, a coworker’s glance, a stain on a shirt, or a clicking sound under the front left wheel. (Turned out to be my brake pads.)

Note that an inference is the converse of an implication; the stimulus implies, the observer infers. The smell of chocolate chips implies the presence of fresh baked cookies in the kitchen. My assumption about their presence is an inference.

The GMAT too makes use of implication and inference in its Reading Comprehension and Critical Reasoning sections. Broadly speaking, there are two sorts of inference questions on the GMAT: global inference questions (which ask you think of a title or conclusion for a passage or argument, or to make a conjecture related to the text as a whole), and more targeted inference questions (related to passage claims, authors’ viewpoints, or tone). Inference questions aren’t hard to spot since they tend to use the words “imply” and “inference” in the stem.

Unlike assumption or strengthen/weaken questions, it is not always useful to come up with a possible answer for inference questions before looking at the actual answer choices. Since passage details often lend themselves to numerous possible inferences, we almost have no choice but to just go through each and every answer choice to find the best fit.

So what’s the most efficient way to handle these problems?  Your best bet is to take a page from the master of inferences himself, Mr. Sherlock Holmes.

If you’ve read his stories then you know of his Jedi-like ability to know all about a person after a single casual glance. In the classic tale “The Red-Headed League,” for example, the good detective immediately deduces that Mr. Jabez Wilson is a former manual laborer who recently went to China simply by examining a few details about the man’s hands.

Holmes didn’t use any sort of secret technology or demonic powers; he just extrapolated from what was right in front of him. In the same way, GMAT questions don’t demand any sort of outside knowledge. Therefore, the first thing you should do for any question that starts, “We can infer from the above argument that…” is to eliminate any answer choices that reference topics outside of the argument’s scope.

Once you remove the irrelevant, try to rule out answer choices that are extreme, or try to substitute similar terms or confuse passage wording. These are harder to see, particularly for global inference questions. One shortcut method, if you’re stuck, is to look for synonyms for words in the answer choices in the text.

CR and RC inference questions invariably have at least a couple of answer choices that are either irrelevant, out of scope, extreme, or manipulative of passage wording. Other questions will try to hit you with answer choices that sound logical but aren’t actually implied by the text. Science topics, for example, may offer answer choices that accurately describe a phenomena but are still wrong since the passage does not say as much.

Eliminate two or three answer choices, and your odds will improve significantly for each question.  If two answers sound both sound totally right to you, re-read the relevant section of the text and go with your gut. After enough practice, hopefully your response to GMAT inference questions will be the same as Mr. Wilson’s after Sherlock Holmes explained how he deduced all of the details of Wilson’s background:

Mr. Jabez Wilson laughed heavily. “Well, I never!” said he. “I thought at first that you had done something clever, but I see that there was nothing in it, after all.”

Jonathan Bethune is a content developer at Knewton.