Exposure to certain chemicals commonly used in elementary schools as cleaners or pesticides causes allergic reactions in some children. Elementary...
GMAT Critical Reasoning : (CR) Questions
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?
Passage Analysis:
| Text from Passage | Analysis |
| Exposure to certain chemicals commonly used in elementary schools as cleaners or pesticides causes allergic reactions in some children. |
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| 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. |
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| 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. |
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Argument Flow:
The argument starts with background info about chemical allergies in schools, then presents evidence of increasing allergy rates in Renston, and concludes with two possible explanations for this increase.
Main Conclusion:
The increase in allergic reactions must be due to either greater chemical exposure or increased sensitivity in today's children compared to 10 years ago.
Logical Structure:
The author uses the nurse reports as evidence to support a conclusion that offers only two possible explanations for the trend. The logic assumes these are the only two reasonable possibilities for the increase.
Prethinking:
Question type:
Assumption - We need to find what must be true for the author's conclusion to hold. The author concludes that the increase in allergic reactions is due to either more chemical exposure OR increased sensitivity in kids.
Precision of Claims
The key claims involve proportional comparisons (proportion of kids with reactions now vs 10 years ago) and causal explanations (either increased exposure OR increased sensitivity must explain the trend).
Strategy
To find assumptions, we need to identify ways the conclusion could be false while keeping the facts intact. The facts we can't question: some chemicals cause reactions, and nurses report more kids coming for treatment now than 10 years ago. We need to find what gaps exist between these facts and the conclusion that it's either more exposure or more sensitivity.
This focuses on the number of nurses, but that's not relevant to our argument. The argument is about the proportion of children with reactions, not the absolute numbers. Even if there were fewer nurses, the proportion of children being treated could still accurately reflect the trend in allergic reactions. This doesn't address the gap between the evidence and conclusion.
This is about whether kids allergic to chemicals are more likely to have other allergies too. But our argument isn't comparing different types of allergies or making any claims about children's general allergy profiles. The conclusion is specifically about reactions to school chemicals over time, so this assumption isn't needed.
This is exactly what we need! The argument assumes that the increase in nurse visits reflects a real increase in reactions, not just changes in behavior about when to send kids to the nurse. If children with allergic reactions were more likely to be sent to nurses now than 10 years ago (maybe due to policy changes or increased awareness), then the increase in nurse visits wouldn't necessarily mean more kids are having reactions. The argument depends on this NOT being the case.
This deals with chemical use in homes, but our argument is specifically about school exposure and school nurse visits. Whether chemicals are used in homes doesn't affect the logic connecting increased school nurse visits to either increased school exposure or increased sensitivity. The argument's scope is limited to schools.
This is about the demographic composition of Renston's population. But since the argument talks about proportions of schoolchildren (not absolute numbers), changes in how many kids live in Renston wouldn't affect the validity of the conclusion. The proportion-based evidence would still support the either/or conclusion about exposure and sensitivity.