Question

Exposure to certain chemicals commonly used in elementary schools as cleaners or pesticides causes allergic reactions in some children. Elementary school nurses in Renston report that the proportion of schoolchildren sent to them for treatment of allergic reactions to those chemicals has increased significantly over the past ten years. Therefore, either Renston’s schoolchildren have been exposed to greater quantities of the chemicals, or they are more sensitive to them than schoolchildren were ten years ago.

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

(Because of copyrights, the complete official question is not copied here. You can access the question here: GMAT Club)

Difficulty: Medium

Accuracy: 71%

Based on: 7750 sessions

Solution

The Story

Exposure to certain chemicals commonly used in elementary schools as cleaners or pesticides causes allergic reactions in some children. – Some children experience allergic reactions if exposed to certain chemicals commonly used in schools.

Elementary school nurses in Renston report that the proportion of schoolchildren sent to them for treatment of allergic reactions to those chemicals has increased significantly over the past ten years. – Nurses in a particular school report that a much higher proportion of children require treatment for allergic reactions to such chemicals in the last 10 years.

Author’s logic:
Since a higher proportion of children are sent to the nurses for treatment of allergic reactions to the chemicals (basis), either exposure or sensitivity has increased (main point).

Gap(s) in logic:
It could be the case that earlier students were not sent to the nurses despite them having allergic reactions.
Maybe teachers used to prescribe some basic medication. But now teachers don’t do it because they fear lawsuits.

Question Stem

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

Prediction:
The author assumes there can’t be any other reason for why a higher proportion of such children are sent to the nurses.

Answer choice analysis

Answer Choice: A

Incorrect

Selected by: 7%

What if the number of school nurses employed by the schools has decreased over the past ten years (negation)?
Even then, the argument still remains valid.
In fact, if despite fewer nurses a higher proportion of children were sent for such treatments, perhaps exposure or sensitivity had increased. So, the negation does not break down the logic of the argument.

Answer Choice: B

Incorrect

Selected by: 5%

Step 1: What does the option mean?
Two groups of children are compared: those who are allergic to the discussed chemicals and those who are not.
What about these groups?
Group 1 is not more likely to be allergic to other things.
In other words, group 1 is equally or less likely to be allergic to other substances.
Now, Is there an assumption in the argument? The argument is about the treatment of, exposure to and sensitivity to certain specific types of chemicals. How children react to other chemicals or substances, and whether the reaction varies are irrelevant to the argument.

Answer Choice: C

Correct

Selected by: 71%

Statement: The likelihood of sending such children to a nurse has not increased in the ten years.
This one is in line with our initial understanding. The statement supports the argument.
And, if such children are more likely to be sent to nurses now than they were ten years ago (negation) then the argument breaks down. In that case, to still conclude that the reason must be either exposure or sensitivity doesn’t make sense.
The basis for the conclusion was the fact that a higher proportion of children are sent to the nurses for allergy treatments. And if the chances of sending such children had increased, then increased exposure or sensitivity would not be the reason.

Answer Choice: D

Incorrect

Selected by: 10%

Doesn’t matter. Whether these chemicals are used in houses is irrelevant. The conclusion is pretty broad in this regard. It mentions ‘exposed to greater quantities of the chemicals’. The conclusion does not discuss ‘where’ children get exposed.
So, even if the chemicals are commonly used as cleanness in houses (negation), the argument still remains valid.

Answer Choice: E

Incorrect

Selected by: 7%

Proportion of the town’s population = #  of children at the school / population of the town
Whether this proportion has changed, and if it has, in which direction are immaterial to the argument. Even if the children now make up a larger proportion (negation), the argument is not impacted.

If you have any doubts regarding any part of this solution, please feel free to ask in the comments section.


Anish Passi

GMAT Coach

With over a decade of GMAT training experience, top 1 percentile scores on the CAT and GMAT, Anish is one of the most qualified GMAT coaches in India. He has founded and served as Director in two ed-tech startups in the past. An alumnus of IIM Ahmedabad and McMaster University, Canada, he strongly believes in the right way of learning, and in learning to grow and not just to get a score, an admission or a job. Anish offers private tutoring and live-online classroom courses. His sessions are often sprinkled with jokes that only he finds funny (you’ve been warned). To connect with him, write to him at a@TheGMATCo.com

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