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# Exposure to certain chemicals commonly used in elementary schools

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

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Updated on: 17 Apr 2006, 05:05
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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.

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[Reveal] Spoiler: OA

Originally posted by joemama142000 on 17 Apr 2006, 03:26.
Last edited by joemama142000 on 17 Apr 2006, 05:05, edited 2 times in total.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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22 Feb 2009, 11:34
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nitindas wrote:
Option 'C' says that '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' -- If this were to be assumed then the statement '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' becomes false.

Can anybody explain plz.

IMO 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'- is the assumption so try to negate this statement and negation will hurt the conclusion.

'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'
In this case more children are sent to the nurse therefore the incidences are reported more and allergic reactions has not increased significantly.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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17 May 2011, 11:01
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close call between A and C here.

Negating A means that as the number of nurses has decreased,even though the number of children sent remains the same,children seen/nurse has increased.

Negating C means it is more likely that children will be sent to the nurses now than earlier.

C seems closer to the conclusion here. The number of nurses hasn't been discussed in the stem.

Hence C preferred.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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30 Sep 2012, 03:37
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Question Stem
Which of the following is an assumption on which the argument depends?
Assumption Question- Ask the question - what is required so that the conclusion is true. Also use the negation test on last 2 option choices.

Argument
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 school children 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.

Pre-thinking
More children became aware of the symptoms and reported the same. So they were sent to the nurses.

A. The number of school nurses employed by Renston’s elementary schools has not decreased over the past ten years.
INCORRECT ANSWER - This answer could have been correct if the argument did not mention "PROPORTION". Even if the nurses reduced, the proportion calculation would still remain the same -
$$\frac{No of students sent}{Total no of students}$$

B. Children who are allergic to the chemicals are no more likely than other children to have allergies to other substances.
INCORRECT ANSWER - "other substances" is outside the scope of the argument

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.
CORRECT ANSWER - If the chance that children are sent to the nurse is same, then the conclusion is true.

Negation Test - 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 - So this statement rules out both the options in the conclusion. So this is the CORRECT ANSWER.

D. The chemicals are not commonly used as cleaners or pesticides in houses and apartment buildings in Renston.
INCORRECT ANSWER - If not used commonly then the chemical may not be a reason. It weakens the conclusion.

E. Children attending elementary school do not make up a larger proportion of Renston’s population now than they did ten years ago.
INCORRECT ANSWER - "larger proportion of Renston’s population" - this does not matter. The argument is not talking about this but the proportion of students sent to nurses.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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17 Apr 2013, 14:28
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mun23 wrote:
subhashghosh 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?

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.

I picked d.Need every option`s explanation

Hi Mun23.
My pleasure to help.

Premise: exposure to chemical ==> allergic reactions
Premise: the proportion of schoolchildren sent to them for treatment of allergic reactions increase
Conclusion: more children exposed to greater quantities of the chemicals, or they are more sensitive

Assumption: proportion = children who got allergy and were brought to hospital / Total children.
KEY is "children actually were brought to hospital". If they got allergy and NOT went to hospital, they are not counted.

A. The number of school nurses employed by Renston’s elementary schools has not decreased over the past ten years.
Wrong. Out of scope.

B. Children who are allergic to the chemicals are no more likely than other children to have allergies to other substances.
Wrong. Out of scope

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.
Correct. This is the assumption above.

D. The chemicals are not commonly used as cleaners or pesticides in houses and apartment buildings in Renston.
Wrong. SHELL GAME. "are NOT used in houses & apartment" DOES NOT MEAN "are used in school". What if the chemical are not commonly used in both school & houses.==> We cannot conclude children exposed to greater quantities of the chemicals.

E. Children attending elementary school do not make up a larger proportion of Renston’s population now than they did ten years ago.
Wrong. We cannot conclude the number of children increased or decreased, because the proportion also depends on the total population that may increase or decrease.

Hope it helps a little bit.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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Updated on: 22 Feb 2015, 03:43
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Took a lot of time to decide between C und E.
We have a sound argument here, so don't look for GAP in this case, we need a DEFENDER (see CR Bible) here, which eliminates a possible WEAKENER.

1) The argument says there are 2 possible reasons - a weakener could be a 3rd possible reason, which we eliminate.
2) Let's talk about proportions, relevant proportion here is a # of children sent with allergic reactions / # of school children

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 --> CORRECT. That could be our 3rd reason and is actually a good weakener. So sliminating this one would DEFEND our argument.

E. Children attending elementary school do not make up a larger proportion of Renston’s population now than they did ten years ago --> This one talks about the wrong proportion - so, it doen't weaken the argument. We need a proportion children with allergie / children and not children / population of the city.
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Originally posted by BrainLab on 21 Feb 2015, 05:06.
Last edited by BrainLab on 22 Feb 2015, 03:43, edited 1 time in total.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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21 Feb 2015, 12:26
sanjoo wrote:
I got wrong.. I chose option B..

In assumption question , when argument give few reasons or cause of something.. then in assumption question, usually we do say that no anything else is the cause of that effect..
i mean in this question,
, 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.

Two reasons have been given for proportion of children of elementry school have increased to elergy..
So i chose B because it says that there is no anyother substance that affect those children.

will anyone explain where m wrong?? experts?

I can see your confusion, but you have to be careful about the exact language in the question. This question is about "certain chemicals", but answer choice B is talking about chemical other than those "certain chemicals". It's what we would call "out of scope" of the argument because it's not talking about the same chemicals.

Your rationale about other causes is perfectly suited to C. It eliminates the possibility that people are just more likely to run to the nurse when experiencing a reaction.

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

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25 Mar 2015, 17:06
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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 schools [#permalink]

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04 Sep 2016, 11:25
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Expert's post
geek_mnnit wrote:
I agree with abrakadabra not able to understand why A is wrong?
Experts,
Can you please explain the rational behind A not being correct? thanks!

The passage does not state that the number of students reporting PER NURSE has increased - it states that the PROPORTION OF STUDENTS reporting has increased. Therefore it does not matter, how many nurses are there. Hence A is wrong.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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22 Nov 2016, 19:27
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Hi,

I have stuck on this question. I read posts, but still I couldn't get why the answer is C

This is how i understand the argument:
Premise: Exposure to chemicals --> causes allergic reaction in children
Premise: Nurses report that number of children sent to them for chemical allergy treatment has increased over the past ten years
Conclusion: Children have been exposed to greater amount of chemicals or children are more sensitive than children 10 years ago.

As derived from conlcusion: In either way more children will be allergic, hence more children will go to the nurse.

Answer C states that: "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". In my opinion, C goes against the conclusion. And when negated it supports the conclusion: 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

Could someone please explain what is wrong with my reasoning?

Thanks

In this particular question, option C invalidates the original conclusion by providing an alternate reason.

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.

Negate option 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 --> The negated statement means that the children are not sent to nurses because of increased exposure to chemicals or increased sensitiveness but are just more likely to be sent to nurses now than 10 years ago when they exhibited allergic reactions.
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Re: Exposure to certain chemicals commonly used in elementary schools [#permalink]

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11 Jun 2017, 16:26
Deba2017 wrote:
In the passage it says :

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.

In Option 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.

As per option C , less number of children reporting to nurses now compared to the number of reporting 10 years back , so obviously rate of reporting should be decreased. But the passage depicts opposite picture.

Thanks chiragmishra93 for the explanation!

According to the argument, the increase in the proportion of schoolchildren sent to the elementary school nurses is due to either greater exposure to the chemicals or a greater sensitivity to the chemicals. But what if 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? That could explain the increase in the proportion of schoolchildren sent to the elementary school nurses, even if students' exposure and sensitivity to the chemicals has not changed.

Thus, in order for the argument to hold, the author must assume that 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. Choice (C) is the correct answer.
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Re: Exposure to certain chemicals commonly used in elementary schools   [#permalink] 11 Jun 2017, 16:26
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