Leachate is a solution, 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 leachate 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 sent 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.

I dont have an OA/OE for this, but thought Id put it up for discussion amongst our great community here.

E.

(A) The ability to predict the volume of escaping landfill leachate would help solve the disposal problem.
NO. There is no mention about this.

(B) If any water permeates a landfill, leachate will escape into the environment.
NO. Leachate will only escapes if it exceeds the holding capacity of the landfil.

(C) No sewage treatment plants are capable of handling leachate.
NO. Seems extreme statement ( but not all sewage plants are capable of handling the highly contaminated water.)

(D) Some landfill leachate is send to sewage treatment plants that are incapable of handling it.
NO. (Some instead of 'MOST')

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

I am with you Walker. I think it's D also.

E for me.

D is close, but as per question not all sewage plants are capable of handling contaminated water, this means that there is a probability that lechate goes to such a plant , while D suggests that it definitely goes to a few such plants, which may not be true.
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GGG (Gym / GMAT / Girl) -- Be Serious

Its your duty to post OA afterwards; some one must be waiting for that...

(A) The ability to predict the volume of escaping landfill leachate would help solve the disposal problem.
-- New Inforamtion. Hence A can be eliminated.

(B) If any water permeates a landfill, leachate will escape into the environment.
-- Thats against the premise. Hence B cannot be the correct answer choice.

(C) No sewage treatment plants are capable of handling leachate.
Exaggerated answer choice. Hence C can be eliminated.

(D) Some landfill leachate is send to sewage treatment plants that are incapable of handling it.
This answer choice is like a shell game. Though it is possible, some leachate might be send to sewage treatment plants (incapable of handling), however it is not necessary that it has to be true. Hence we cannot infer this from the argument.

(E) If leachate does not escape from a landfill into the environment, then the landfill’s capacity to hold liquids has not been exceeded.
-- From the premise, we can clearly infer that it is true. Hence E has to be correct answer choice.

to resolve for answer choice D, you can use the venn diagram. Take the objects - leachate, sewage treatment, capable sewage treatment and see if the D comes true. It doesn't. Hence D is an incorrect answer choice.

Thank You.

Thanks,
Akhil M.Parekh

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.
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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.
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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...

Marked E as well.(stick to basics)
D was really tempting though

great explanation by testluv. +1