Quarter Wit, Quarter Wisdom: Beware of Assumption in GMAT Critical Reasoning Options

Quarter Wit, Quarter WisdomSometimes, while evaluating the answer choices in in strengthen/weaken questions, we unknowingly go beyond the options and make assumptions about what they may imply if we were to have additional pieces of data. What we have to remember is that we do not have this additional information – we have to judge each option on its own merits, only. Let’s discuss this in detail with one of our own practice GMAT questions:

In 2009, a private school spent $200,000 on a building which housed classrooms, offices, and a library. In 2010, the school was unable to turn a profit. Therefore, the principal should be fired.

Each of the following, if true, weakens the author’s conclusion EXCEPT:

(A) The principal was hired primarily for her unique ability to establish a strong sense of community, which many parents cited as a quality that kept children enrolled in the school longer.
(B) The new library also features a seating area big enough for all students to participate in cultural arts performances, which the head of school intends to schedule more frequently now.
(C) The principal was hired when the construction of the new building was almost completed.
(D) A significant number of families left the school in 2010 because a favourite teacher retired.
(E) More than half of the new families who joined the school in 2010 cited the beautiful new school facility as an important factor in their selection of the school.

This is a weaken/exception question, so four of the five answer choices will weaken the argument, while the fifth option (which will be the correct answer) will either not have any impact on the argument or it might even strengthen it. As we know, such questions require a bit more effort to answer, since four of the five options will definitely be relevant to the argument. The important thing is to focus on what we are given and not assume what the various answer options may or may not lead to. Let’s understand this:

The gist of the argument:

  • Last year, a lot of money was spent to construct a new building with many amenities.
  • This year, the school did not see a profit.
  • Hence, fire the principal.

Based on the two given facts – “a lot of money was spent to make the building in 2009” and “the school did not see a profit in 2010” – the author has decided to fire the principal. Many pieces of information could weaken his stance. For example:

  • It was not the principal’s decision to construct the building.
  • The school’s revenue in 2010 took a hit because of some other factor.
  • The school’s losses reduced by a huge amount in 2010 and the probability of it seeing a profit in 2011 is high.

Information such as this could improve the principal’s case to stay. We know that for this particular question, there will only be one option that does not help the principal.

You will have to choose the answer choice which, with the given information, does not help the principal’s case. Let’s look at the options now:

(A) The principal was hired primarily for her unique ability to establish a strong sense of community, which many parents cited as a quality that kept children enrolled in the school longer.

With this answer choice, we see that the principal was hired not to increase school profits, but for another critical purpose. Perhaps the school’s finance department is in charge of worrying about profits, and so the head of that department needs to be fired! This answer choice makes a strong case for keeping the principal, and hence, weakens the author’s argument.

(B) The new library also features a seating area big enough for all students to participate in cultural arts performances, which the head of school intends to schedule more frequently now.

If true, this statement would have no impact on whether or not the principal should be fired. It describes an amenity provided by the new building and how it will be used – it neither strengthens nor weakens the principal’s case to stay, hence, this is the correct answer choice. But let’s look at the rest of the options too, just to be safe:

(C) The principal was hired when the construction of the new building was almost completed.

This tells us that the new building was not her decision. So if it did not have the desired effect, she cannot be blamed for it. So it again helps her case.

(D) A significant number of families left the school in 2010 because a favourite teacher retired.

This answer choice shows that there was another reason behind the school’s loss in profit. The construction of the building could still be a good idea that leads to future profits, which the principal’s case and weakens the author’s argument.

(E) More than half of the new families who joined the school in 2010 cited the beautiful new school facility as an important factor in their selection of the school.

For some reason, this is the answer choice that often trips up students. They feel that it doesn’t help the principal’s case – that because the new building attracts students, if there are losses, it means that the loss is due to a fault with the new building, and thus, the principal is at fault. But note that we are assuming a lot to arrive at that conclusion. All we are told is that the new building is attracting students. This means the new building is serving its purpose – it is generating extra revenue. The fact that the school is still experiencing losses could be explained by many different reasons.

Since the author’s decision to fire the principal is based solely on the premise that a lot of money was spent to construct the new building, which now seems to serve no purpose (because the school experienced losses), this answer choice certainly weakens the argument. The option tells us that the principal’s decision to make the building was justified, so it helps her case to stay with the school.

After examining each answer choice, we can see that the answer is clearly B. Remember, in Critical Reasoning questions it is crucial to come to conclusions only based on the facts that are given – creating assumptions based on information that is not given can lead you to fall in a Testmaker trap.

Getting ready to take the GMAT? We have free online GMAT seminars running all the time. And, be sure to follow us on FacebookYouTubeGoogle+, and Twitter!

Karishma, a Computer Engineer with a keen interest in alternative Mathematical approaches, has mentored students in the continents of Asia, Europe and North America. She teaches the GMAT for Veritas Prep and regularly participates in content development projects such as this blog!

Assumption vs. Strengthen Critical Reasoning Questions: What’s the Difference?

GMATI had a discussion with a tutoring student the other day about the distinction between Assumption and Strengthen questions in the Critical Reasoning section. The two categories feel similar, after all. They are different, however, and the difference, as with most Critical Reasoning questions, lies mainly in the texture of the language that would be most appropriate for a correct answer in either category.

To illustrate, let’s take a simple argument: Dave opens a coffee shop in Veritasville called Dave’s Blends. According to surveys, Dave’s Blends has the best tasting coffee in the city. Therefore, Dave’s Blends will garner at least 50% the local market.

First, imagine that this is a simple Strengthen question. In order to strengthen this somewhat fanciful conclusion, we’re going to want strong language. For example: Virtually all coffee drinkers in Veritasville buy coffee daily from Dave’s. That’s a pretty good strengthener. The statement increases the likelihood that Dave’s Blends will dominate the local market. But an answer choice such as, “Some people buy coffee at Dave’s,” would be a lousy choice, as the fact that Dave’s has at least one customer is hardly a compelling reason to conclude that it will get to at least a 50% market share.

Now imagine that we take the same argument and make it an Assumption question. The first aforementioned answer choice is now much less appealing. Can we really assume that virtually everyone in town will get their coffee at Dave’s? Not really. If Dave’s has 51% of the market share, it doesn’t mean that virtually everyone gets their coffee there. But now consider the second answer choice – if we’re concluding that Dave’s will get at least half of the local market, we are assuming that some people will purchase coffee there, so now this would be a good answer.

The difference is that in a Strengthen question, we’re looking for new information that will make the conclusion more likely. In an Assumption question, we’re looking for what is true based on the conclusion.  Put another way, strong language (“virtually everyone”) is often desirable in a Strengthen question, whereas softer language (“some people”) is usually more desirable in an Assumption question.

Let’s see this in action with a GMAT practice question:

For most people, the left half of the brain controls linguistic capabilities, but some people have their language centers in the right half. When a language center of the brain is damaged, for example by a stroke, linguistic capabilities are impaired in some way. Therefore, people who have suffered a serious stroke on the left side of the brain without suffering any such impairment must have their language centers in the right half. 

Which of the following is an assumption on which the reasoning in the argument above depends?

(A) No part of a person’s brain that is damaged by a stroke ever recovers.
(B) Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.
(C) Strokes tend to impair linguistic capabilities more severely than does any other cause of damage to language centers in the brain.
(D) If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them.
(E) It is impossible to determine which side of the brain contains a person’s language centers if the person has not suffered damage to either side of the brain.

First, let’s break this argument down:

Conclusion: People who suffer a stroke on the left side of the brain and don’t’ suffer language impairment have language centers in the right half of the brain.

Premises: Most people have language centers on the left side of the brain, while some have them on the right. Damage impairs linguistic capabilities.

This is an Assumption question, so we’re looking for what is be true based on the way the premises lead to the conclusion. Put another way, softer language might be preferable here. Now let’s examine each of the answer choices:

(A) Notice the extreme language, “No part…ever recovers“. Can we really assume that? Of course not – some portion might recover. No good.

(B) We don’t know this. Imagine someone has a part of his or her brain removed and this part of the brain doesn’t contain a language center. Surely we can’t assume that this person will have no language impairment at all. No good.

(C) Again, notice the extreme language, “…more severely than other cause. Can we assume that a stroke is worse than every other kind of brain trauma? Of course not. No good.

(D) Now we’re talking. Here, we are given more generous language: damages at least one of them. “At least one” is a pretty low bar. Remember that the conclusion is that someone who suffers a left-brain stroke and doesn’t have language impairment must have language centers on the right side. Well, that only makes sense if there’s some damage somewhere on the left. This answer choice looks good.

(E) Notice again the extreme language, “…it is impossible“. There may be some other way to assess where the language centers are. No good.

Therefore, our answer is D.

Takeaway: Strengthen questions and Assumption questions are not identical. In a Strengthen question, we want a strong answer choice that will make a conclusion more likely. In an Assumption question we want a soft answer that is indisputable based on how the premises lead to the conclusion. Attention to details in the language (some vs. most vs. all) is the key.

Plan on taking the GMAT soon? We have GMAT prep courses starting all the time. And be sure to follow us on FacebookYouTubeGoogle+ and Twitter!

By David Goldstein, a Veritas Prep GMAT instructor based in Boston. You can find more articles written by him here.