How to Solve Critical Reasoning Questions on the GMAT

A quote often attributed to (2nd US President) John Adams states that “facts are stubborn things”. In everyday life, we are often confronted with various personal opinions or subjective viewpoints on everything from politics (more horses and bayonets or less?) to fashion (can you believe what Miley Cyrus wore last week) to love (you complete me). However everyone understands that personal opinions are, well, personal. They vary from one individual to another and two people can have completely different beliefs on the exact same issue.

This is what makes facts so compelling. Their objectiveness removes all bias from the situation. Some people may think I’m more handsome than Brad Pitt (although they are few and far between), but I can unequivocally guarantee that I am taller than him. Facts provide certainty that there is no real debate over the issue, and this is why they’re so appealing. It’s also why they can be so tempting on the GMAT, in particular in Critical Reasoning.

In general, any Critical Reasoning argument you see on the GMAT will be flawed. The exam will not provide you with an air-tight, impossible-to-disprove argument (like, say, OJ’s alibi in 1994). The arguments will always have imperfections that can be exploited, like a small tear in a fabric that you can rip apart. As such, any “facts” provided will necessarily be true, but won’t necessarily be relevant to the situation or supportive of the proposed conclusion.

In particular, statistics about absolute numbers will often be meaningless on the exam. The classic trap will be something along the lines of “more people are injured cooking dinner than swimming with sharks, therefore it’s safer to swim with sharks than to cook dinner”. While the facts may technically be true, they clearly do not support the conclusion as we would need some kind of indication as to the percentage of people who are injured while participating in the activity versus those who emerge unscathed. Percentages are very useful things in statistics, absolute numbers are less so (although 38% of statistics are made up on the spot).

Of course, the base case is but one situation where the facts provided do not shore up the author’s conclusion. Consider the following example:

Highways 24 and 105 each have relatively equal traffic loads, meaning their daily vehicle counts are virtually equal. According to records maintained by the State Department of Transportation, Highway 24 had fewer vehicle accidents last year than did Highway 105. Therefore, driving on Highway 24 is safer than driving on Highway 105.

Which of the following, if true, would most strengthen the conclusion above?

(A)   Highway 105 runs through lowlands notorious for poor visibility due to heavy fog, while Highway 24 does not.

(B)   More than twice as many highway patrol officers are assigned to Highway 105 than to Highway 24.

(C)   The emergency rooms of the hospital located along Highway 105 report considerably more injuries than do those of the hospital near Highway 24.

(D)   Highway 24 had more fatal accidents than Highway 105 last year.

(E)    Highway 105 was built with traditional asphalt, while Highway 24 was built with a newer, more inexpensive asphalt substitute.

Almost mechanically, when provided with absolute number data, my instinct is to look for the percentage information above. However this is not the answer here, as the question already addresses this issue in the first sentence, and furthermore we are looking to reinforce the conclusion, and not undermine it. Since this is a strengthen question, so we should be able to predict some kind of answer.

What is the conclusion of this question? The conclusion language “Therefore” indicates that we want to support the fact that highway 24 is safer than highway 105. The evidence is that there are more accidents on the 105. In order to strengthen this, we should look for another reason that the 105 is more dangerous (and ~4.5 times bigger) than the 24 without using the number of accidents. We are trying to reinforce the purported conclusion, so we want to provide more potential reasons why this must be true. Let’s look through the answer choices:

A)     This creates another reason why the 105 is more dangerous: it’s hard to see anything! This supports the conclusion and could easily be the correct answer. On test day we could stop here, but let’s keep going just to be sure.

B)      Even if you think that having more officers assigned to a highway makes it safer, this choice should make the 105 safer, not less safe.  Otherwise, what difference does the number of assigned officers make to the safety of the road? 180° in the best case, irrelevant in the worst.

C)      This choice can be tempting, but do we know whether the number of accidents at the nearby hospital has anything to do with the safety of the nearest highway? There could easily be an asbestos mine (or a Justin Bieber concert) nearby that would easily explain the numerous injuries. This does not actually strengthen the conclusion.

D)     Again, fatal accidents on the 24 would make the 105 safer, if fatal injuries were a concern. 180°.

E)      The difference in material is not elaborated upon in any meaningful way. Perhaps the more inexpensive substitute is less sticky and cars slide off more easily? Perhaps it is safer because it is newer? We cannot evaluate this choice without more information, so this cannot be correct.

Answer choice A seemed correct right off the bat, and indeed it is the correct answer to this question. The other choices can be tempting, but if you evaluate each one you can see how they do not really strengthen the conclusion in any tangible way. Only answer choice A gives us another option as to why the highway could be considered dangerous, and therefore strengthens the conclusion without having to depend on the facts presented in the stimulus.

In particular on statistics questions, be weary of stats and know how to support them or weaken them as the question requires. As Mark Twain put it “Facts are stubborn things, but statistics are pliable.” Knowing how to ply them on test day will help you increase your score, and that’s a fact no one can debate.

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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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