Every year many people become ill because of airborne mold

[chitrangada.maitra]

Source: mgmat

Every year many people become ill because of airborne mold spores in their homes. After someone becomes ill, specialists are often hired to eradicate the mold. These specialists look in damp areas of the house, since mold is almost always found in places where there is substantial moisture. If one wishes to avoid mold poisoning, then, one should make sure to keep all internal plumbing in good condition to prevent leakage that could serve as a breeding ground for mold.

Which of the following is an assumption on which the argument depends?
A) Mold itself does not create moisture.
B) Most homeowners know enough about plumbing to determine whether theirs is in good condition.
C) Mold cannot grow in dry areas.
D) No varieties of mold are harmless.
E) Mold spores cannot be filtered from the air.

Answer: A

My question is:
On what basis do i eliminate C?
If C is incorrect i.e. mold can grow in dry areas, then checking internal plumbing etc cannot prevent mold poisoning - which means the conclusion cannot stand.
Please let me know if I am missing something here.

[gokul_nair1984]

If C is incorrect i.e. mold can grow in dry areas, then checking internal plumbing etc cannot prevent mold poisoning - which means the conclusion cannot stand.

This option is already stated in the premises:Premises indicate mold spores are almost always found in moist places so there are chances it grows in dry places in some cases.

The words 'almost always' do not mean 100% true per se.This means the premise itself says that mold could grow in some other areas(probably dry ones/ semi dry , we don't know). Also if the mold caused the moisture , then checking all plumbings would not be enough( which is stated by the conclusion and cannot be contradicted)

Furthermore, "Mold cannot grow in dry areas" is an extreme answer, so we search for a better one instead.

(A) option is a causation correlation example wherein we assume that if a caused b to occur, then the occurrence of b will not cause a to occur.

Most conspicuoulsy, the conclusion that " If you want to avoid molds, ensure your plumbings are in order" is not affectd in anyway whether the assumption that ,"Mold cannot grow in dry areas" holds good or not but it is deeply affected by the fact whether it is the mold that inturn causes moisture because if that were true then plumbing would never help!!! Thus the mold itself should not create moisture is most appropriate.

[chitrangada.maitra]

Hi Gokul!

I agree with the causation correlation logic - If "A" & "B" occur together, we can assume that 'A' caused 'B' if we we know that 'B' didnt cause 'A' etc..

My problem is on what basis do I eliminate option C?
I gather from your explanation that we can avoid mold poisoning more by fixing internal plumbing than by any other method since mold is almost always found in places where there is substantial moisture. For e.g by assuming that mold does not cause moisture and checking internal plumbing, I can get rid of 90% mold but by assuming that mold grows in dry areas and not getting plumbing fixed, I can get rid of only 10% mold.

That makes sense to me!
Thanks,

[mschwrtz]

Gokul has already answered that question, when he characterized C as an extreme answer. That's precisely how you eliminate it.

Now, perahps you want to know why it doesn't weaken, rather than why it's a poor answer to a GMAT weaken question, but that could be a different issue.

One answer to that question is that the argument suggests only that avoiding moisture is necessary for preventing mold, not that it is sufficient. C undermines only the claim that preventing moisture is sufficient.

Now, that's all accurate, but it takes us away from the real issue here, which is as Gokul said the leap from correlation to causation.

The conclusion is If one wishes to avoid mold poisoning, then, one should make sure to keep all internal plumbing in good condition to prevent leakage that could serve as a breeding ground for mold. We might gloss this as,

avoiding mold poisoning--->avoiding breeding mold--->preventing leakage--->maintain plumbing

where the "--->" represents logical implication, not causation. avoiding mold poisoning requires avoiding breeding mold, not avoiding mold poisoning causes avoiding breeding mold.

Though the arrow doesn't represent causation here, there is a causal element: the argument assumes that moisture causes mold.

One piece of evidence for this is
mold is almost always found in places where there is substantial moisture.

So, just as Gokul suggested.

[as2764]

how about (B) that says Most homeowners know enough about plumbing to determine whether theirs is in good condition. can this not be a valid assumption? because, as discussed above, the conclusion says: keeping plumbing in check will avoid mold poisoning.

which in turn implies that homeowners do know how to keep plumbing in check. and SO, if they don't know how to do so, then they wouldn't be able to avoid mold poisoning.

let's try a reversal:
most homeowners do NOT know enough about plumbing to determine whether theirs is in good condition. thus, homeowners may NOT be able to avoid mold poisoning.

(B) might sound like an ancillary assumption. could you, Ron, or Stacey clarify my contention between A and B? thanks

[jnelson0612]

how about (B) that says Most homeowners know enough about plumbing to determine whether theirs is in good condition. can this not be a valid assumption? because, as discussed above, the conclusion says: keeping plumbing in check will avoid mold poisoning.

which in turn implies that homeowners do know how to keep plumbing in check. and SO, if they don't know how to do so, then they wouldn't be able to avoid mold poisoning.

let's try a reversal:
most homeowners do NOT know enough about plumbing to determine whether theirs is in good condition. thus, homeowners may NOT be able to avoid mold poisoning.

(B) might sound like an ancillary assumption. could you, Ron, or Stacey clarify my contention between A and B? thanks

I think this is a great question and B is an appealing answer. However, even if the homeowners do not know enough about plumbing to determine whether theirs is in good condition, they could hire experts to make this determination. That the homeowners themselves have this ability is not necessary to reach the conclusion "one should make sure to keep all internal plumbing in good condition to prevent leakage that could serve as a breeding ground for mold". For example, I know nothing about cars, but I keep my car in good condition by taking it to the dealer for regular maintenance.

This argument is clearly a causal argument; very basically, it says that leakage causes mold (or at the very least leakage creates favorable conditions in which mold can grow, thus indirectly causing mold). If I conclude that X causes Y, then the assumption for a causal argument must always be that it is not in fact Y which is causing X. Notice how A puts this together nicely.

[as2764]

However, even if the homeowners do not know enough about plumbing to determine whether theirs is in good condition, they could hire experts to make this determination. That the homeowners themselves have this ability is not necessary to reach the conclusion "one should make sure to keep all internal plumbing in good condition to prevent leakage that could serve as a breeding ground for mold". For example, I know nothing about cars, but I keep my car in good condition by taking it to the dealer for regular maintenance.

Jamie, thanks for your reply. you have a good point, and for a person like me, this requires some mental effort to go out of the box and think like that. in fact, it would really be hard for me to see this distinction esp. under time pressure. the car analogy you gave is good, because the stimulus says one should make sure to keep all internal plumbing in good condition -- something that can be done in many ways and does not require prior knowledge of doing so. how do you think i can characterize the wrong answer choice (B)?

This argument is clearly a causal argument; very basically, it says that leakage causes mold (or at the very least leakage creates favorable conditions in which mold can grow, thus indirectly causing mold). If I conclude that X causes Y, then the assumption for a causal argument must always be that it is not in fact Y which is causing X. Notice how A puts this together nicely.

i saw the causality too, but i think there can be more than one assumptions. because whenever i see a correlation-type of CR problem, the first thing i do is look for disproving reverse causation and also, alternate causation. another analogy would be, say, a disease and a symptom existed simultaneously, so the disease caused the symptom. the assumptions here could be:
a. the symptom didn't lead to the disease.
b. another disease (there can be many) didn't cause the symptom.

the correlation and causality sounds to me like a chicken-and-egg thing. but, does this suggest that there are patterns i need to be aware of? and that i have a pre-planned mechanism to identify and approach a problem like this.

[jnelson0612]

You make really good points Ashish, and I can tell that you think deeply about this. That is great!

How would I characterize B? Hmm, it's hard to type it into a certain category (out of scope, opposite, etc). I'd probably characterize it as "attractive but not as necessary as A". If I'm looking for an assumption, the best assumption will be the one that is most necessary to reach the conclusion. I can't disagree with your assertion that there are often multiple assumptions leading to a conclusion. That is true, and I may have overstated my case before. However, we need to choose the best answer on the GMAT, so we have to choose the assumption that is most necessary to reach the conclusion.

As you know, if you are struggling with two assumption answer choices, it can be helpful to negate both of them and see which one does most harm to the conclusion.

Let's review:
Premise: Mold causes illness. Specialists eradicating the mold look in damp areas of the house, since mold is almost always found in places with substantial moisture.
THEREFORE
Conclusion: If one wishes to avoid mold poisoning, one should make sure to keep all internal plumbing in good condition to prevent leakage that could serve as a breeding ground for mold.

Let's take both of these answer choices, negate, and see which one hurts our conclusion the most:
A) Mold itself creates moisture.
To me, this hurts a lot. In this case, what is the point of keeping the internal plumbing from leaking? We find out that mold is causing the moisture, not the other way around, so preventing leaking will NOT prevent mold.
B) Most homeowners do NOT know enough about plumbing to determine whether theirs is in good condition.
I can understand your contention that this hurts the conclusion. However, is it AS damaging as A? You make the call.

I can understand your concerns about identifying the types of problems. Honestly, it sounds like you've got a pretty good grip--when you see a correlation in the premise that leads to a causal conclusion, immediately identify that reversal causality must be ruled out (as an assumption). This sort of "formula" is pretty common on causal GMAT questions; if A and B occur together, and A is thought to cause B, then we must assume that B is not causing A. If I can find an assumption stating this latter part, I would feel confident in choosing it.

[as2764]

Let's take both of these answer choices, negate, and see which one hurts our conclusion the most:
A) Mold itself creates moisture.
To me, this hurts a lot. In this case, what is the point of keeping the internal plumbing from leaking? We find out that mold is causing the moisture, not the other way around, so preventing leaking will NOT prevent mold.
B) Most homeowners do NOT know enough about plumbing to determine whether theirs is in good condition.
I can understand your contention that this hurts the conclusion. However, is it AS damaging as A? You make the call.

here's how i would boil the argument's conclusion down to the best of my ability:
do A --> avoid B
keep internal plumbing in check to prevent leakage --> avoid mold poisoning

negation of (A) says mold creates moisture, so doing A is useless -- rock solid.
negation of (B) says homeowners don't know to keep plumbing in check. this attacks A (the suggested action to achieve a certain result B), saying A is not happening as homeowners don't know how to check--and don't themselves do the--plumbing. can this not mean that they have no clue how it's to be done, including whether they need to hire someone?

(A) is definitely the best, but (B), in my opinion, is still debatable.

I can understand your concerns about identifying the types of problems. Honestly, it sounds like you've got a pretty good grip

thanks for following up on the discussion, Jamie--this CR problem would be too hard to forget :)

[jnelson0612]

(A) is definitely the best, but (B), in my opinion, is still debatable.

thanks for following up on the discussion, Jamie--this CR problem would be too hard to forget :)

Aha! We have agreement, cool!

Yes, trust me, I see the attractiveness of B, but we do have to go with which one is best. If the GMAT gave you one good answer and four duds it wouldn't be a very discriminating test.

Nice thinking Ashish; again, I really like how you are putting a lot of thought into these. :-)

[as2764]

Nice thinking Ashish; again, I really like how you are putting a lot of thought into these. :-)

thanks to you as well for following up.
trust me, Jamie, dissecting arguments really grinds my gears, but it's inevitable for me to do so :D

[jnelson0612]

got it, ashish. :-)

[cooldude1986]

Nice Discussion

[jnelson0612]

Nice Discussion

Thanks; I agree. :-)

[denny798]

If C is incorrect i.e. mold can grow in dry areas, then checking internal plumbing etc cannot prevent mold poisoning - which means the conclusion cannot stand.

This option is already stated in the premises:Premises indicate mold spores are almost always found in moist places so there are chances it grows in dry places in some cases.

The words 'almost always' do not mean 100% true per se.This means the premise itself says that mold could grow in some other areas(probably dry ones/ semi dry , we don't know). Also if the mold caused the moisture , then checking all plumbings would not be enough( which is stated by the conclusion and cannot be contradicted)

Furthermore, "Mold cannot grow in dry areas" is an extreme answer, so we search for a better one instead.

(A) option is a causation correlation example wherein we assume that if a caused b to occur, then the occurrence of b will not cause a to occur.

Most conspicuoulsy, the conclusion that " If you want to avoid molds, ensure your plumbings are in order" is not affectd in anyway whether the assumption that ,"Mold cannot grow in dry areas" holds good or not but it is deeply affected by the fact whether it is the mold that inturn causes moisture because if that were true then plumbing would never help!!! Thus the mold itself should not create moisture is most appropriate.

I have been trying to understand the logic here but am not quite sure if it makes sense.

Logic: Molds are almost always found in damp areas -> to avoid mold poisoning, keep internal plumbing in good condition

I understand that answer A is stating the causation corrleation here. So A is an assumption of the passage. However, if A were to be true i.e. if mold itself DOES create moisture then this would imply that mold DOES grow in dry areas, which is essentially the same meaning of answer C "mold cannot grow in dry areas". So, wouldn't C also be an assumption of the passage? Also, I find that A and C are similar in how extreme the statements are.

Is my logic incorrect here? Please advise.