Critical Reasoning

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 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.

OA-->focus focus

IMO D

We have to find an option which must be true according to the argument and require no assumption for its validity..

"Most landfill leachate is send directly to sewage treatment plants, but not all sewage plants are capable of handling the highly contaminated water."

This line in the argument indicates the validity of Op D.

C is extreme and D is okay....

took adv of options... 49sec... havent focused much

Guys,

Why not E???

I am finding Op E worth giving a thought too. I think the answer is E.

Can we have the OA plz.

guys this q is a bit tricky n c if u can spot the whole concept...
OA tomm
maybe someone got it right already

Hi champmag... You missed the word "unpredictable quantities" than means zero too...

I got my mistake, its a situation like this

if A causes B then

B(NOT)---> A (NOT) always true...for this now i think, Op E is correct

Regarding Op D, earlier i was wrong i think...i read somewhere for some question that MOST may contain 100% also...

It may be possible that all the liquid send to the capable sewers..

If X, then Y --> if not Y then not X. So chosing (E).

i will go with E here.
for D stimilus says Most - it can mean all or not all.
Some may mean all or may be 1 0r 2 or may be more than that.
option D is not as conclusive as opton E is.

1. Leachate develops when water is in a landfill site
2. If the capacity of the landfill is exceeded leachate will escape
3. A method is needed to dispose of leachate
4. Not all sewage treatment plants can handle it

A. Incorrect. Not an important point in this passage

B. Incorrect. No. It only escapes when capacity is exceeded

C. Incorrect. Clearly the passage implies that some are and some are not

D. Incorrect. The passage never states that it is sent there. If anything you might be able to infer it is not sent right now, wllowing it to build up and eventually escape when capacity is exceeded

E. Correct. This is exactly what the passahe tells us in sentence 2. It can only escape if the capacity is exceeded so for it not to escape then there is room for more garbage.

This is most likely an LSAT question. You won't get formal logic-heavy questions in GMAT CR.

Anyhow, "X if and only if Y" means that X and Y are both sufficient and necessary for each other*. In other words, they are a matched set: either they both happen or they both don't happen.

In this question we have: "If and only if the landfill's capacity to hold liquids is exceeded does the leachate escape into the environment..." So, we know that these two events:

I the landfill's capacity to hold liquid being exceeded
II leachate escaping into the environment

are each sufficient and necessary for the other. Choice E can be inferred (and is the correct answer) because it is saying that leachate escaping into the environment is necessary for the landfill's capacity to hold liquid being exceeded.

Choice D is wrong because although the passage establishes that "not all sewage plants are capable of handling [the leachate]" we don't know if any of the leachate is actually sent to these underperforming sewage plants--the leachate may very well be sent only to sewage plants that ARE capable of handling it. So Choice D could be false, and cannot be inferred.

*Formally:
"X if AND only if Y" yields:

(I) "X if Y" AND (II)"X only if Y". Thus, the following two pairs of contraposing conditional statements follow:

(I) "X if Y" = IF Y THEN X (or, contrapositively, IF NOT X THEN NOT Y)

AND

(II) "X ONLY IF Y" = IF X THEN Y (or, contrapositively, IF NOT Y, THEN NOT X)

OA is E
congrats cham... for getting it right the first time
@ testluv u guessed it right ....it is an LSAT q n though the logic is slightly heavy , i found this a gr8 question to sharpen my skills with inferences

my take
remember D uses a quantifier some which doesnt' match with "Most landfill leachate is send directly to sewage treatment plants"

rahul_tgsp wrote: my take
remember D uses a quantifier some which doesnt' match with "Most landfill leachate is send directly to sewage treatment plants"

Hi Rahul,

actually, if "most x are y", then you CAN infer that "some x are y".

"Most" means "more than half," and

"Some" means "at least one."

Given that both of these definitions allow for the possibility of "all," if you know that "all x are y" then you also know that "more than half of x are y" or "most x are y". And you also know that "at least one x is a y" or "some x are y".

So, in this tree, you can infer DOWNWARDS but NOT upwards:

ALL
MOST
MANY/SOME

Choice D is wrong because even if certain sewage plants can't process leachate, it may be the case that no leachate is sent to these plants in the first place. (That is, all the leachate may be sent to sewage plants that CAN process it.)

Wow..Nice one luv,,,copy pasted to my dB

So, in this tree, you can infer DOWNWARDS but NOT upwards:

ALL
MOST
MANY/SOME