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# Leachate is a solutions, frequently highly contaminated,

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Kaplan GMAT Instructor
Joined: 21 Jun 2010
Posts: 66
Location: Toronto
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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01 Jul 2010, 11:31
5
Quote:
Could anybody clarify why D is incorrect?

Quote:
E is a mere paraphrasing of the stimulus --- there is no inference per se here.

Hi,

an inference is an implied conclusion. But on a GMAT inference question, if you see an answer choice that must be true based on the stimulus, you should always automaticlaly select it. There are two reasons for this: a) what you think is a simple paraphrase may actually have something new in it, and can thus be regarded as a proper inference; and b) some questions simply ask you to treat the passage as true, and select a choice that "must be true"--in these cases, the correct answer may even be a restatement of one of the statements in the passage.

In a GMAT inference question, a choice that must be true based on one or more statements in the passage is ALWAYS automatically correct.

Thus, the the four wrong answers are things that could be false.

Let's apply this approach to this question.

In the passage we learn that leachate gets into the environment if and only if the landfill’s capacity to hold liquids is exceeded. This means two things. First, whenever the landfill's capacity is exceeded, some leachate will definitely escape into the environment. Second, if the landfill's capacity is NOT exceeded, then there is nothing to worry about. (Formally, the landfill's capacity being exceeded is both a sufficient and necessary condition for leachate escaping into the environment).

Let's consider choices D and E:

(D) Some landfill leachate is send to sewage treatment plants that are incapable of handling it.

Well, I can see why this is tempting. After all, the last sentence told us that leachate (well, most of it anyways) is sent to sewage treatment plants, and that some sewage treatment plants can't handle leachate. But did we learn whether any leachate goes to the plants that can't hanlde it? Nope. Fine, there may be some plants that can't handle leachate, but it could easily be the case that no leachate is actually sent to these plants--that leachate is only sent to plants that CAN handle leachate.

Thus, choice D could be false, and we can eliminate it.

(E) If leachate does not escape from a landfill into the environment, then the landfill’s capacity to hold liquids has not been exceeded.

Well, we learned that if the landfill's capacity were exceeded that leachate will for sure escape into the environment. So, if no leachate escaped, then capacity was not exceeded (because if capacity were exceeded, leachate would have escaped!). (Many of you will recognize this concept as the "contrapositive").

Thus, choice E must be true (based on the passage). Thus, choice E must be correct.

TAKEWAY: in GMAT inference questions stay very CLOSE to the passage. If you see a choice that must be true, it is undoubtedly the correct answer. If you see a choice that could be false, it is undoubtedly an incorrect answer.

SOMETHING YOU SHOULD KNOW ABOUT THIS QUESTION: this is an LSAT or else an LSAT-like question. It tests formal logic in a way that GMAT CR never would.
VP
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Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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01 Jul 2010, 12:18
Excellent! I am impressed - completely!

I missed the point that the leachates may after all NOT land up at any of the plants incapable of handling them! Gosh!

The other thing that threw me off and which I now remember is having failed to answer a similar question - albeit as I now recollect - was an assumption question - in which one of the (incorrect) answer choices was a paraphrase from the passage - and which I immediately jumped at and selected; turned out it was wrong. That kinda stayed in my memory and now when I saw this question that alarm went off again - because choice E sounded very much like a paraphrase and I felt it was a trap. It is a no brainer practically to see that E is true but well oh well... my bad...

Testluv wrote:
Quote:
Could anybody clarify why D is incorrect?

Quote:
E is a mere paraphrasing of the stimulus --- there is no inference per se here.

Hi,

an inference is an implied conclusion. But on a GMAT inference question, if you see an answer choice that must be true based on the stimulus, you should always automaticlaly select it. There are two reasons for this: a) what you think is a simple paraphrase may actually have something new in it, and can thus be regarded as a proper inference; and b) some questions simply ask you to treat the passage as true, and select a choice that "must be true"--in these cases, the correct answer may even be a restatement of one of the statements in the passage.

In a GMAT inference question, a choice that must be true based on one or more statements in the passage is ALWAYS automatically correct.

Thus, the the four wrong answers are things that could be false.

Let's apply this approach to this question.

In the passage we learn that leachate gets into the environment if and only if the landfill’s capacity to hold liquids is exceeded. This means two things. First, whenever the landfill's capacity is exceeded, some leachate will definitely escape into the environment. Second, if the landfill's capacity is NOT exceeded, then there is nothing to worry about. (Formally, the landfill's capacity being exceeded is both a sufficient and necessary condition for leachate escaping into the environment).

Let's consider choices D and E:

(D) Some landfill leachate is send to sewage treatment plants that are incapable of handling it.

Well, I can see why this is tempting. After all, the last sentence told us that leachate (well, most of it anyways) is sent to sewage treatment plants, and that some sewage treatment plants can't handle leachate. But did we learn whether any leachate goes to the plants that can't hanlde it? Nope. Fine, there may be some plants that can't handle leachate, but it could easily be the case that no leachate is actually sent to these plants--that leachate is only sent to plants that CAN handle leachate.

Thus, choice D could be false, and we can eliminate it.

(E) If leachate does not escape from a landfill into the environment, then the landfill’s capacity to hold liquids has not been exceeded.

Well, we learned that if the landfill's capacity were exceeded that leachate will for sure escape into the environment. So, if no leachate escaped, then capacity was not exceeded (because if capacity were exceeded, leachate would have escaped!). (Many of you will recognize this concept as the "contrapositive").

Thus, choice E must be true (based on the passage). Thus, choice E must be correct.

TAKEWAY: in GMAT inference questions stay very CLOSE to the passage. If you see a choice that must be true, it is undoubtedly the correct answer. If you see a choice that could be false, it is undoubtedly an incorrect answer.

SOMETHING YOU SHOULD KNOW ABOUT THIS QUESTION: this is an LSAT or else an LSAT-like question. It tests formal logic in a way that GMAT CR never would.
Kaplan GMAT Instructor
Joined: 21 Jun 2010
Posts: 66
Location: Toronto
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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01 Jul 2010, 14:46
1
Quote:
The other thing that threw me off and which I now remember is having failed to answer a similar question - albeit as I now recollect - was an assumption question - in which one of the (incorrect) answer choices was a paraphrase from the passage - and which I immediately jumped at and selected; turned out it was wrong. That kinda stayed in my memory and now when I saw this question that alarm went off again - because choice E sounded very much like a paraphrase and I felt it was a trap.

I'm glad you bring this up!

As discussed in my post above, in an inference or must be true type of question, a choice that restates or paraphrases a part of the passage is automatically correct.

However, in an assumption question, a choice that restates evidence is automatically wrong. Why? Because assumptions are, by definition, UNSTATED.

So, we can say:

In assumption questions, choices that restate evidence are automatically incorrect; in inference/must be true, choices that restate evidence are automatically correct.
VP
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Schools: Wharton (R2 - submitted); HBS (R2 - submitted); IIMA (admitted for 1 year PGPX)
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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01 Jul 2010, 14:50
Testluv wrote:
Quote:
In assumption questions, choices that restate evidence are automatically incorrect; in inference/must be true, choices that restate evidence are automatically correct.

That rule is an ideal candidate for a GMAT CR101 COURSE... perfect!
VP
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Posts: 1030
Schools: Wharton (R2 - submitted); HBS (R2 - submitted); IIMA (admitted for 1 year PGPX)
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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01 Jul 2010, 14:53
dwivedys wrote:
Testluv wrote:
Quote:
In assumption questions, choices that restate evidence are automatically incorrect; in inference/must be true, choices that restate evidence are automatically correct.

That rule is an ideal candidate for a GMAT CR101 COURSE... perfect!

of course we all know this fact - assumptions are unstated premises and inferences are siituations that MUST be true based on the passage...one gets the true import only after passing through the grind I must say... Well lesson learnt! Thanks a lot Testluv...you've got the knack to pinpoint the true pain areas... I truly appreciate it... You get my kudos...
Kaplan GMAT Instructor
Joined: 21 Jun 2010
Posts: 66
Location: Toronto
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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01 Jul 2010, 18:19
1
[quote2dwivedys]Well lesson learnt! Thanks a lot Testluv...you've got the knack to pinpoint the true pain areas... I truly appreciate it... You get my kudos...[/quote2]

Thanks so much for the kind words!
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Joined: 18 Oct 2008
Posts: 114
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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02 Jul 2010, 10:24
Marked E as well.(stick to basics)
D was really tempting though

great explanation by testluv. +1
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Joined: 23 Jun 2010
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GMAT 1: 710 Q49 V37
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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31 Oct 2010, 03:12
Testluv wrote:
Quote:
Could anybody clarify why D is incorrect?

SOMETHING YOU SHOULD KNOW ABOUT THIS QUESTION: this is an LSAT or else an LSAT-like question. It tests formal logic in a way that GMAT CR never would.

Gr8 Explanation...+1 from my side..

As you said above that GMAT would never test these stuffs so is solving LSAT questions a bad idea to prepare for GMAT CR?
Director
Joined: 04 Jun 2016
Posts: 556
GMAT 1: 750 Q49 V43
Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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27 Jul 2016, 09:04
ANSWER IS SUPER EASY E

Remembering the definition of inference will help to get the correct answer in under 10 seconds
(i) Inference is a logical conclusion that can be drawn using one or more premises given in the argument.
(ii)Also noteworthy is to remember that an inference must never be said or written explicitly in the argument (otherwise it will become just another premise)

E) If leachate does not escape from a landfill into the environment, then the landfill's capacity to hold liquids has not been exceeded.
We can infer this from the premise in the argument. "If and only if the landfill's capacity to hold liquids is exceeded does the leachates escape into the environment"
No leaking of leachate=Landfill still have capacity to hold leachate.

CORRECT) Answer is E

asaf wrote:
Leachate is a solutions, frequently highly contaminated, that develops when water permeates a landfill site, If and only if the landfill's capacity to hold liquids is exceeded does the leachates escape into the environment, generally in unpredictable quantities, A method must be found for disposing of leachate. Most landfill leachate is send directly to sewage treatment plants, but not all sewage plants are capable of handling the highly contaminated water.

Which one of the following can be inferred from the passage?

(A) The ability to predict the volume of escaping landfill leachate would help solve the disposal problem.

(B)If any water permeates a landfill, leachate will escape into the environment.

(C) No sewage treatment plants are capable of handling leachate.

(D) Some landfill leachate is send to sewage treatment plants that are incapable of handling it.

(E) If leachate does not escape from a landfill into the environment, then the landfill's capacity to hold liquids has not been exceeded.

Can you deny D or E?

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Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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22 Apr 2017, 04:22
Solutions 1:-

For inference questions we must always be able to prove the answer choice by referring back to the argument. The answers are usually

(1) Paraphrase of one or more of the premises in the argument
(2) Logical conclusion from one or more premises in the argument

If and only if the landfill's capacity to hold liquids is exceeded does the leachate escape into the environment,

E is nothing but a paraphrase of whats given in the argument i.e using (1) above

but not all sewage plants are capable of handling the highly contaminated water

Choice D is Some landfill leachate is sent to sewage treatment plants that are incapable of handling it.Do we know that leachate has been sent to some sewage plants from whats given in the argument?? NO....

If choice D was

Some sewage treatment plants are incapable of handling the leachate sent to them.-> YES this would be a logical conclusion i.e. using (2) above
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Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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04 Oct 2017, 13:01
Once we find the contrapositive, the answer becomes very apparent. We are given that "If and if the capacity is exceeded, then leachates escapes". A typical if X - Y statement. If we take the contrapositive of this, we get: If the leachates does not escape, then the capacity has not been exceeded". This is exactly what option E is saying, hence the correct answer!
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Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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14 Dec 2017, 07:15
asaf wrote:
Leachate is a solutions, frequently highly contaminated, that develops when water permeates a landfill site, If and only if the landfill's capacity to hold liquids is exceeded does the leachates escape into the environment, generally in unpredictable quantities, A method must be found for disposing of leachate. Most landfill leachate is send directly to sewage treatment plants, but not all sewage plants are capable of handling the highly contaminated water.

Which one of the following can be inferred from the passage?

(A) The ability to predict the volume of escaping landfill leachate would help solve the disposal problem.

(B)If any water permeates a landfill, leachate will escape into the environment.

(C) No sewage treatment plants are capable of handling leachate.

(D) Some landfill leachate is send to sewage treatment plants that are incapable of handling it.

(E) If leachate does not escape from a landfill into the environment, then the landfill's capacity to hold liquids has not been exceeded.

There are three claims in this stimulus.

1. If, and only, if the landfill's capacity to hold liquids is exceeded does the leachate escape into the environment.
2. Most landfill leachate is sent directly to sewage treatment plants.
3. Not all sewage plants are capable of handling the highly contaminated water.

We need to find an answer that we can infer from one or more of these statements.

(A) may be true and seems to make sense, but is an unsupported prediction. It may not help solve the problem, however.
(B) contradicts the stimulus. The first claim says that leachate will escape into the environment if, and only if, the landfill's capacity is exceeded - not if leachate permeates a landfill.
(C) is not necessarily true. We know that not all sewage plants are capable of handling the highly contaminated water. That does not mean that no sewage plants are capable of handling leachate.
(D) attempts to combine the second and third statement. However, no inference can be made from combining a SOME statement in the third claim and a MOST statement in the second claim. According to these two claims, it's possible that all leachate is sent directly to only those sewage treatment plants that are capable of handling the contaminated water.
(E) must be true. This is part of what can be inferred from the contrapositive of the first statement.
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Re: Leachate is a solutions, frequently highly contaminated,  [#permalink]

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05 Aug 2019, 14:26
Can you fix the grammar and formatting please? This is the most poorly constructed problem in terms of syntax and formatting that I've ever seen on GMAT Club..
Re: Leachate is a solutions, frequently highly contaminated,   [#permalink] 05 Aug 2019, 14:26

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