Inference on GMAT Reading Comprehension

When you are asked to infer on your own, how far can you go in your own direction?  Not far at all!  How far can your inference go from the text?  Not far at all!

 

The art of inferring on the GMAT

On the GMAT Verbal section, Reading Comprehension will ask you to infer things.  To infer means: to draw as a conclusion, by your own deductive powers, some statement that is not stated directly.  Right there, that’s one requirement for a good GMAT inference: if it’s stated directly, in black and white, it can’t be an inference.  An inference has state something different from is stated explicitly.  That, though, leads to the other big requirement.  A good GMAT inference is not stated explicitly, but it is only a hair’s breadth away from what is stated explicitly.  In other words, if the text explicitly states A and B and C, then the correct inference D is a statement that any logical person would consider absolutely obvious and undeniable, given A & B & C.  If it is possible for A & B & C to be true, and for D not to be true, then D is absolutely not a correct inference on the GMAT.   A good GMAT inference must be an absolutely and unarguably necessary consequence of what is stated explicitly.  In fact, this is precisely what can make the first requirement tricky.  If D is such an ineluctable consequence of A & B & C, it may be that when you read A & B & C, you automatically assumed D, and therefore consider it “already explicitly stated.”  Be careful.  The good inference will be that statement that you unavoidably assume, on the basis of what is explicitly stated, but if you look carefully, that statement itself is not explicitly written in the text.

 

An example

For simplicity, let’s consider the shortest Reading Comprehension passage in the world: just a single sentence.

Roger slammed on the brakes of his car, and narrowly avoided a collision with the truck.

Suppose that’s the whole of our passage, and we are asked to make an inference.  The following statements would not work as inferences, because they are, in one way or another, stated explicitly.

1. Roger used the brakes of his car.

2. Roger did not hit the truck.

3. No car accident occurred here.

4. Roger came close to having a car accident here.

Those all re-state information in the sentence.  Notice, incidentally, if Roger skidded past the truck and hit another car — yes, that would be an accident, but that’s a continuation of the story beyond what’s explicitly stated. We have to base our answers on the passage as it appears.

The following statements are not good inferences because they are debatable: each one could be true, but everything explicitly stated could happen without any one them happening.

5. Roger had been driving fast.

6. Roger’s car has good brakes.

7. Roger has good reflexes.

8. The truck was at rest.

9. The truck was initially moving slower than Roger’s car.

10. Roger’s car came to rest.

11. Roger’s car left skid marks.

12. Roger’s car would have suffered expensive damage in a collision with the truck.

Any of those could be true, but none of them has to be true.  Perhaps this scenario, Roger initially was going fast, and therefore slamming on the brakes would have left skid marks, but perhaps this was all at extremely slow speeds, say, in a crowded parking lot.  The truck might have been at rest, or Roger could have been following the truck and catching up to it, or Roger & the truck could have been moving head-on toward each other, which raises the possibility that the truck was moving faster — say Roger was moving 10 mph south, the truck was moving 15 mph north, and they both slammed on the brakes and avoided each other.  We have no idea how this event would compare to another driver and/or another car, and therefore no way of evaluating the speed of Roger’s reflexes or the condition of his brakes.  We know nothing about the damage Roger’s car would have sustained in the collision, first of all, because we don’t know whether it was a high-energy or low-energy impact, and also because we don’t know the condition of Roger’s car: is it something already banged up, so that an extra dent wouldn’t make a difference? or is it something incredibly solid, like a Hummer, that is more likely to inflict damage than be damaged?  We don’t know.    We don’t know whether Roger came to a stop, or whether he slowed down, swerved around the truck, and kept going: admittedly, that probably would not be the safest driving procedure, but we cannot rule it out on the basis of what is explicitly stated in the passage.  None of those eight statements is a certain logical deduction, so none is a proper GMAT-worthy inference.

What, then, would be a valid GMAT inference?  Consider this statement:

13) If Roger had continued in his path of motion without using his brakes, his car would have hit the truck.

We know that Roger “slammed” on his brakes —- that is, used a lot of force on his brakes —- and he “narrowly missed” a collision, in other words, came very close to having a collision: in other words, he “almost” had a collision.  Even using his brakes to maximum effect, he almost had a collision.  “Almost” means: any slight change in the negative direction would have been enough to bring about the collision.  Well, not using the brakes at all — that’s not a minor change, but rather a catastrophic change.  That is enough to imply, unavoidably, that if he had not used his brakes at all, he would have had the collision.  There’s really no substantial argument against that.

While this passage is entirely unrealistic in its brevity, this little exercise demonstrates the spirit of GMAT RC inference: not directly stated, but an absolutely unavoidable consequence of what is explicitly stated.

 

Practice question

Try your hand at this free GMAT RC inference question.

https://gmat.magoosh.com/questions/1207

 

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  • Mike MᶜGarry

    Mike served as a GMAT Expert at Magoosh, helping create hundreds of lesson videos and practice questions to help guide GMAT students to success. He was also featured as "member of the month" for over two years at GMAT Club. Mike holds an A.B. in Physics (graduating magna cum laude) and an M.T.S. in Religions of the World, both from Harvard. Beyond standardized testing, Mike has over 20 years of both private and public high school teaching experience specializing in math and physics. In his free time, Mike likes smashing foosballs into orbit, and despite having no obvious cranial deficiency, he insists on rooting for the NY Mets. Learn more about the GMAT through Mike's Youtube video explanations and resources like What is a Good GMAT Score? and the GMAT Diagnostic Test.