Exposure to certain chemicals commonly used in elementary : GMAT Critical Reasoning (CR)
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# Exposure to certain chemicals commonly used in elementary

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Exposure to certain chemicals commonly used in elementary [#permalink]

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10 Dec 2009, 16:13
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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?

A. The number of school nurses employed by Renston’s elementary schools has not decreased over the past ten years.
B. Children who are allergic to the chemicals are no more likely than other children to have allergies to other substances.
C. Children who have allergic reactions to the chemicals are not more likely to be sent to a school nurse now than they were ten years ago.
D. The chemicals are not commonly used as cleaners or pesticides in houses and apartment buildings in Renston.
E. Children attending elementary school do not make up a larger proportion of Renston’s population now than they did ten years ago.

Can somebody explain ?

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[Reveal] Spoiler: OA
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11 Dec 2009, 09:16
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I think it should be C.

The nurse observes that a greater proportion of the students are being sent to her to be treated for allergic reactions. She concludes that either students are more sensitive to the chemicals or that they are being exposed to more of the chemicals. The questions asks on what assumption her argument depends.

C. States states that children are not more likely to be sent to the nurse for allergic reactions to chemicals tens years ago. To draw her conclusion, she must assumes that children are just as likely to be sent to the nurse now as they were before. If children are most likely to be sent to the nurse than before, then the increase can be a result of that, and not exposure to more chemicals or increased sensitivity.
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Re: Nice and confusing CR ?! [#permalink]

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17 Dec 2009, 12:52
seluka wrote:
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?

Give away: cleaners or pesticides causes allergic/proportion of schoolchildren who are allergic reactions to those chemicals has increased significantly over the past ten years/ conclusion: increase because either 1.) expose to greater quantity or 2.) children are more sensitive.
A. The number of school nurses employed by Renston’s elementary schools has not decreased over the past ten years. -->#of nurses is irrelevant
B. Children who are allergic to the chemicals are no more likely than other children to have allergies to other substances. -->other substances are irrelevant
C. Children who have allergic reactions to the chemicals are not more likely to be sent to a school nurse now than they were ten years ago. --> suggests that children are sent NOT because of those above 2 reasons,for example, NOT BECAUSE the school nurse is more accessible, NOT BECAUSE parents aware more of the allegic and told childeren to go to school nurse. (Assumption Q: alternative to the conclusion type.)
D. The chemicals are not commonly used as cleaners or pesticides in houses and apartment buildings in Renston. -->weakening
E. Children attending elementary school do not make up a larger proportion of Renston’s population now than they did ten years ago. --> children proportion to population is irrelevant
Can somebody explain ?
[Reveal] Spoiler:
C

My ans is C
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Re: Nice and confusing CR ?! [#permalink]

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18 Dec 2009, 17:54

The argument is based on the number of students visiting the nurses over the 10 year span.
For a conclusion this number needs to be constant all throughout. Therefore the argument is based on this assumption
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Re: Exposure to certain chemicals commonly used in elementary [#permalink]

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06 Nov 2013, 07:28
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Re: Exposure to certain chemicals commonly used in elementary [#permalink]

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09 Nov 2013, 01:58
IMO C:
Premise:Nurses have reported a increase in proportion of school children sent to them for treatment of allergic reactions over the past ten years.
conclusion: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.
Now the premise and conclusion would stand true if the number of children getting and reporting allergic reactions due to exposure to these chemicals has increased and not just number of children reporting allergic reactions has increased....
Only C satisfies this condition....
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Re: Exposure to certain chemicals commonly used in elementary [#permalink]

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25 Oct 2014, 04:07
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I read in most of the answer explanations that choice A is irrelevant. Choice A is wrong, but certainly not irrelevant, because if the number of nurses decrease and the number of children remain constant, then every nurse will be treating more children than he / she used to 10 years ago.

But this assumption assumes that the number of children have remain same / not decreased, thus the choice A holds wrong.
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Re: Exposure to certain chemicals commonly used in elementary [#permalink]

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02 Mar 2015, 07:04
Choice C here, as it is assumed that nurse report cases more often leading to sn increase of accidents
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Re: Exposure to certain chemicals commonly used in elementary [#permalink]

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15 Mar 2015, 17:33
Choice C is the best answer.

The conclusion essentially gives two options, that children are more sensitive to chemicals or that there are more chemicals. The evidence of that (or premise), is that the proportion of children sent to them has increased over the last ten years, so we know we are looking for something that eliminates any other reason (other than those given in the conclusion) for a greater proportion of children to have gone to the nurse. C does a perfect job of that.

The other answers are wrong, because:
A is irrelevant, the reports are from all nurses not an individual
B is also irrelevant to the conclusion. Other allergies do not affect anything
D doesn't effect how much they are used, just eliminates one area they could have affected children
E the proportion of children to the overall population doesn't say anything about the proportion of children being sent to the nurse for chemical allergies
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Exposure to certain chemicals commonly used in elementary [#permalink]

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25 Mar 2015, 16:06
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Hi there,

Argument Deconstructed

- Background (Fact): some chemicals used in elementary schools cause allergic reactions in children.
- Premise (Fact): Nurses in one particular school say that in the past 10 years, a bigger proportion of school children have been sent to them for treatment of these specific allergic reactions.
- Conclusion (Opinion): Only two explanations are possible: 1-Either children have been exposed to greater quantities of the chemical or 2-they are more sensitive than schoolchildren were ten years ago.

Negation Test
I´ll try to explain this question with the Negation Test. In other words, I will negate each answer choice to see whether the new, negated version hurts the argument or not. The one that does, will be our correct answer.

This tactic is based on the fact that an assumption is a hidden or unstated new premise for the argument. If you address a premise, this will strenghten the argument. If you address a premise but also revert its meaning (Negation Test), this will weaken the argument.

A. The number of school nurses employed by Renston’s elementary schools HAS DECREASED over the past ten years.
So what? Irrelevant

B. Children who are allergic to the chemicals are MORE LIKELY than other children to have allergies to other substances.
So what? This doesn´t actually explain the rise in the proportion of children sent to the nurses in the past 10 years.

C. Children who have allergic reactions to the chemicals are MORE LIKELY to be sent to a school nurse now than they were ten years ago.
Waaaaait a minute. This would crash the argument. The author stated that there could be only 2 reasons for the rise in number of children sent to nurses (exposure to greater quantities or more sensitiveness). If we negate this AC, this would imply that there is another (a third) possible cause.

D. The chemicals ARE commonly used as cleaners or pesticides in houses and apartment buildings in Renston.
So what? Completely irrelevant.

E. Children attending elementary school DO MAKE UP a larger proportion of Renston’s population now than they did ten years ago.
So what? This one tries to confuse you with the concept of proportions. Anyway, negating this answer doesn´t hurt the argument.
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Re: Exposure to certain chemicals commonly used in elementary [#permalink]

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02 Apr 2016, 18:37
I went with C
my initial assumptions:
households use more of these chemicals, so children get exposed to greater quantity
continuous exposure -> deterioration of health and thus go to doctor more often.

C looks like a good assumption.
if we negate it, then the conclusion is shattered. children before, even if they had allergy reaction, were not sent to the doc.
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Re: Exposure to certain chemicals commonly used in elementary [#permalink]

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16 Apr 2016, 08:21
UmangMathur wrote:
I read in most of the answer explanations that choice A is irrelevant. Choice A is wrong, but certainly not irrelevant, because if the number of nurses decrease and the number of children remain constant, then every nurse will be treating more children than he / she used to 10 years ago.

But this assumption assumes that the number of children have remain same / not decreased, thus the choice A holds wrong.

In my opinion as well, A is not irrelevant. I chose C as it made more sense but A definitely could be the reason. Also thanks for pointing out why it is incorrect.
Re: Exposure to certain chemicals commonly used in elementary   [#permalink] 16 Apr 2016, 08:21
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