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Difficult Critical Reasoning Problem from LSAT

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7. Waste management companies, which collect waste for disposal in landfills and incineration plants, report that disposable plastics make p an ever-increasing percentage of the waste they handle. It is clear that attempts to decrease the amount of plastic that people throw away in the garbage are failing.

Which one of the following, if true, most seriously weakens the argument?

A. Because plastics creates harmful pollutants when burned, an increasing percentage of the plastics handled by waste management companies are being disposed of in landfills.
B. Although many plastics are recyclable, most of the plastics disposed of by waste management companies are not.
C. People are more likely to save and reuse plastic containers than containers made of heavier materials like glass or metal.
D. An increasing proportion of the paper, glass, and metal cans that waste management companies used to handle is now being recycled.
E. While the percentage of products using plastic packaging is increasing, the total amount of plastic being manufactured has remained unchanged.



Answer is D.
can anyone explain to me why?

Thanks,
Yvonne
Last edited by yvonne0923 on Thu Mar 10, 2011 2:00 pm, edited 1 time in total.

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by Joe K » Wed Mar 09, 2011 6:06 pm
The argument is using percentages to make a conclusion about numbers, usually something to be wary of.

I think with D, it is possible that the while plastic makes up a higher percentage of the total garbage, the total garbage could be less since less of other garbage is being thrown away.


For example:

Before efforts to decrease plastic thrown away

100 lbs of garbage total
50 lbs plastic (50%)
50 lbs other (50%)

After efforts to decrease amount of plastic thrown away and less paper, metal, and cans being thrown away
40 lbs of garbage
32 lbs plastic (80%)
8 lbs other (20%)


Out of the answers, this seems to have the potential to weaken the argument the most by addressing the actual numbers.

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by yvonne0923 » Wed Mar 09, 2011 7:46 pm
Hi joe,

I should have used the method of percentage to solve this problem, thanks a lot!

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by bubbliiiiiiii » Wed Mar 09, 2011 11:00 pm
E is completely irrelevant to what is being discussed in stimulus.

I think D tries to weaken the argument by saying that most of the substances like metal, paper, etc are recycled so may be plastic would also be recycled which ultimately reduces the new production of plastic.

I guess this is shifting question (I remember reading similar stuff earlier in some post.)

yvonne0923 wrote:
I chose choice E, but the correct answer is D.

Can anyone explain to me why the answer is D?


Thanks, Yvone
Regards,

Pranay

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by mundasingh123 » Thu Mar 10, 2011 5:39 am
Yvonne, U could consider putting the OA in the spoiler. I was in a fix before i read the the line underneath the quest
I Seek Explanations Not Answers

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by AIM GMAT » Thu Mar 10, 2011 5:46 am
IMO D .

D. An increasing proportion of the paper, glass, and metal cans that waste management companies used to handle is now being recycled.

This eliminates the assumption that the amount of waste or % of waste material [type i.e. paper , glass or metal] remains constant .
Thanks & Regards,
AIM GMAT

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by force5 » Thu Mar 10, 2011 10:07 am
true. D should be the answer. " E" is out of scope .

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by yvonne0923 » Thu Mar 10, 2011 2:02 pm
Thanks, mundasingh123, I just modified my post bit, since I am new here, so I'm still trying to figure out how to use this sometime.

mundasingh123 wrote: U could consider putting the OA in the spoiler. I was in a fix before i read the the line underneath the quest