Every year many people become ill because of airborne mold

[tim]

Yes, your logic is incorrect. Your analyses of both A and C seem to take the assumptions as a given and attempt to evaluate whether the conclusion makes sense in light of the assumptions. Because we are looking for a necessary assumption, we cannot rely on the fact that the assumption would help lead to the conclusion. Instead, we need to determine whether negating the assumption destroys the argument. This is what is explained in detail above, and is essentially the opposite of what you have done..

[alrha]

what about "If one wishes to avoid mold poisoning..." does that not assume that (D) No varieties of mold are harmless?

[tim]

Not at all. Let's assume even 99% of mold is harmless. We still want to avoid mold poisoning, so we need to take measures that will ensure that the 1% of mold that actually is harmful doesn't poison us. So we don't need to assume that *no* varieties of mold or harmless, only that not *all* varieties are harmless..

[irr5]

Why can't it be E?

Mold poisoning occurs because spores are in the air. Those spores come from growing mold.

The argument says that the only way to avoid mold poisoning is to keep the internal plumbing in good condition so mold doesn't grow. The implication is that if mold were to grow, mold spores would be released into the homes and cause mold poisoning.

However, it seems that one could avoid the mold poisoning in a different way, by letting the mold grow but filtering out the airborne spores from the air. Since there is another way to avoid mold poisoning (via an air filter), one does not need to keep the plumbing in good condition to avoid mold poisoning.

Thus, I don't see why E could not also be the correct answer.

Can someone help with this?

[tim]

i couldn't find the complete text of this question anywhere in the thread. can you help us by posting the question in its entirety so we can fully discuss your concern?

[irr5]

i couldn't find the complete text of this question anywhere in the thread. can you help us by posting the question in its entirety so we can fully discuss your concern?

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.

[tim]

this is a great opportunity to apply the negation test. negate the answer choices and see which one causes the argument to crumble. if we negate A, that means mold DOES cause moisture. if that's the case, keeping your plumbing dry won't necessarily prevent mold because the causal link (moisture is a breeding ground for mold) is broken, and thus there is no reason to conclude that keeping your plumbing dry will help prevent mold poisoning. consider E on the other hand: if we negate E, then mold spores CAN be filtered from the air. even if that is the case, it still might be a good idea (hence the word "should") to keep the plumbing dry so as to limit the amount of mold that is generated..

[irr5]

this is a great opportunity to apply the negation test. negate the answer choices and see which one causes the argument to crumble. if we negate A, that means mold DOES cause moisture. if that's the case, keeping your plumbing dry won't necessarily prevent mold because the causal link (moisture is a breeding ground for mold) is broken, and thus there is no reason to conclude that keeping your plumbing dry will help prevent mold poisoning. consider E on the other hand: if we negate E, then mold spores CAN be filtered from the air. even if that is the case, it still might be a good idea (hence the word "should") to keep the plumbing dry so as to limit the amount of mold that is generated..

But the question isn't whether it's a "good idea" or not. The question isn't "what should we do limit the amount of mold generated." The argument made in the prompt is that it is necessary to maintain the plumbing if one wishes to prevent mold poisoning. If mold spores can be filtered from the air, then it doesn't matter if the entire basement is covered in mold twenty inches thick because the mechanism by which one gets mold poisoning is through the spores and if there are no spores, there is no mold poisoning. There are many reasons you wouldn't want mold to spread; for example, it might make your basement disgusting. But the prompt specifically says "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." This argument implies that failing to keep the plumbing in good condition will result in mold poisoning. However, one could fail to keep the plumbing in good condition, let the mold get extremely large, and still avoid mold poisoning by filtering the spores from the air.

[tim]

your biggest mistake here is fixating on the exact words i used ("good idea"), which were used simply as a proxy for "should". i maintain that "good idea" is a better approximation of "should" than is the word "necessary" that you used. instead of arguing with my synonyms you need to pay attention to the broader issues i dealt with. by choosing E you are effectively saying that if we could filter mold spores out of the air then there's no reason why we should try to keep the plumbing dry. if you are honest with yourself you will see that even if you can filter the air you should still keep the plumbing dry as an extra precaution (keep in mind that your erroneous use of the word "necessary" totally changes this analysis, and that is why you should not make such an extreme change of language). whether i used "good idea" or "should" does not matter because the end result of the analysis is still the same. ultimately you are also missing one other huge point here, which is that under NO circumstances can we have two correct answers to the question, which is almost word for word what you are asking us to do. even if two answer choices are appealing, you must choose which one is better, and E is definitely not the better choice..

[cumulonimbus]

your biggest mistake here is fixating on the exact words i used ("good idea"), which were used simply as a proxy for "should". i maintain that "good idea" is a better approximation of "should" than is the word "necessary" that you used. instead of arguing with my synonyms you need to pay attention to the broader issues i dealt with. by choosing E you are effectively saying that if we could filter mold spores out of the air then there's no reason why we should try to keep the plumbing dry. if you are honest with yourself you will see that even if you can filter the air you should still keep the plumbing dry as an extra precaution (keep in mind that your erroneous use of the word "necessary" totally changes this analysis, and that is why you should not make such an extreme change of language). whether i used "good idea" or "should" does not matter because the end result of the analysis is still the same. ultimately you are also missing one other huge point here, which is that under NO circumstances can we have two correct answers to the question, which is almost word for word what you are asking us to do. even if two answer choices are appealing, you must choose which one is better, and E is definitely not the better choice..

Hi Tim,

What would be the negation for answer choice
C - No varieties of mold are harmless.
Negated: Some varieties of mold are harmless ?

[tim]

Yes, those two sentences you have given are opposites (i.e. negations) of each other.

[mcmebk]

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.

Dear Jamie

To negate option A, we get "Mold itself does create moisture"; however, this does not necessary make the argument fall apart, since the argument is saying "in order to minimize...not to avoid"...

We might not be able to get rid of the mold positioning for those growing in its own created moisture environment, but we can still minimize it by eliminating other causes by maintaining good conditions of plumbing (unless we make another assumption here: Moisture does not cause mold, rather mold causes moisture, which is not clearly stated anywhere.)

What do you think?

[jlucero]

Dear Jamie

To negate option A, we get "Mold itself does create moisture"; however, this does not necessary make the argument fall apart, since the argument is saying "in order to minimize...not to avoid"...

We might not be able to get rid of the mold positioning for those growing in its own created moisture environment, but we can still minimize it by eliminating other causes by maintaining good conditions of plumbing (unless we make another assumption here: Moisture does not cause mold, rather mold causes moisture, which is not clearly stated anywhere.)

What do you think?

I think you're missing the issue on this one- if mold were to create moisture, then water is not what causes mold, but is a symptom of the mold. If this were the case, then preventing wet areas would not stop mold; mold would simply form in dry areas and make those areas wet.

[Basic6]

Dear Instructors, I have a question and please help me to figure out.

The argument says "one should make sure to keep all internal plumbing in good condition to prevent leakage".
Doesn't it mean that one should keep it in good condition anytime?

I mean, In choice A, although mold create moisture, the moisture will not be a problem because we keep plumbing in good condition anytime.
The moisture that mold creates will be cleaned up at the beginning,
so it will not become a problem that breed mold and thus cause people ill.

In choice B, if people don't know whether their plumbing is in good condition, they cannot prevent mold.
Maybe I think my plumbing's condition is good enough, but in act it is not.
And If I have to think in the way that " you don't have to know whether it is in good condition. You can find an expert to help you.",
don't I think too much in CR questions?

If I'm wrong, please correct me.
Thanks!

[ajaym8]

Dear Instructors, I have a question and please help me to figure out.

The argument says "one should make sure to keep all internal plumbing in good condition to prevent leakage".
Doesn't it mean that one should keep it in good condition anytime?

I mean, In choice A, although mold create moisture, the moisture will not be a problem because we keep plumbing in good condition anytime.
The moisture that mold creates will be cleaned up at the beginning,
so it will not become a problem that breed mold and thus cause people ill.

In choice B, if people don't know whether their plumbing is in good condition, they cannot prevent mold.
Maybe I think my plumbing's condition is good enough, but in act it is not.
And If I have to think in the way that " you don't have to know whether it is in good condition. You can find an expert to help you.",
don't I think too much in CR questions?

If I'm wrong, please correct me.
Thanks!

If I may help, (instructors, please correct me if I am wrong here).

Doesn't it mean that one should keep it in good condition anytime?

What I gather from your input is that you are not thinking too much, but not thinking in the right direction/structured manner as GMAT wants you to think. Maybe you have not presented your complete thinking here, so I may be wrong.
Anyway, the conclusion is that plumbing should be in good condition so that mold poisoning is avoided. Wait, how does good plumbing avoid mold poisoning ? Aren't these 2 different ideas ? Yes, they are. To connect these 2 ideas, the argument reasons that mold is almost always found in damp areas & damp areas are formed due to bad plumbing (leakage is mentioned). This means damp places serve as breeding grounds for mold. This means that damp/moist places cause mold.

Now let's come to your thoughts regarding option A

I mean, In choice A, although mold create moisture, the moisture will not be a problem because we keep plumbing in good condition anytime.

How can you say moisture caused by mold will not be a problem. Good plumbing is NOT affecting the moisture here. Think about it. You have great plumbing in your home, but those molds are creating moisture of their own, then what effect will good plumbing have on moisture ? None !

The moisture that mold creates will be cleaned up at the beginning,
so it will not become a problem that breed mold and thus cause people ill.

Wait, you are saying mold created moisture, it got cleaned up by experts and problem solved. Maybe, yes. But we are concerned about the conclusion. The conclusion says plumbing should be in good condition to avoid mold poisoning. It cites good plumbing as a remedy for eliminating damp places and consequently the mold. In your quote, you are not bringing the plumbing into the picture. And this leads the thinking to nowhere.
Option A breaks the conclusion by citing mold-produced-moisture as the cause of moisture and thus DIVERTS away from the plumbing issue.
That's why it is correct. Provides alternate explanation.

Does this help?

Thanks,