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#6 - Manufacturers of writing paper need to add mineral

kan1dice
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Okay, so I'm going through the answer choices and I understand why the correct answer is correct and why the other answers are incorrect. However I am not completely sure as to why D is incorrect. It confused me. Could someone please explain it to me? :-?
Claire Horan
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Writing paper is White :arrow: added mineral filler to paper pulp
No filler added to paper products :arrow: grayish

Narrow down the conclusion of the argument:
"if writing paper made from recycled paper comes to replace other types of writing paper, paper manufacturers will have to use more filler than they now use." Why will they have to do this? Because they want to make the paper white. But the conclusion doesn't say that. It's an unstated assumption.

Check that with the assumption negation technique. If the paper doesn't need to be white, does the conclusion still hold? No, if the paper doesn't need to be white, it's unclear why manufacturers would need additional mineral filler.

Therefore, choice C is the right answer because it matches best to my prephrase that the paper doesn't need to be white.

I generally think that there is no need to explain why a random, perhaps irrelevant answer is wrong when we've prephrased the right answer. The primary question is, "Why is C right and what did I misunderstand that led me to exclude C from consideration?" But because you ask, let's try the assumption negation technique with D.

When we negate "(D) Beyond a certain limit, increasing the amount of filler added to paper pulp does not increase the whiteness of the paper made from the pulp," it becomes that increasing the amount of filler added continues to increase the whiteness of the paper forever. Does this attack the conclusion? No. Does it matter at all to the conclusion of whether recycled paper manufacturers will have to use more filler? No. So, it's an incorrect answer.
kan1dice
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Thank you for answering my question. I could not find a complete explanation for this question on any other site. I read a Power Score article that gave me the advice to go through my questions whether I got them right or wrong and analyze them. Since this has been working to my benefit, it has become important to me that I be able to not only understand why the right answer is correct but also why each answer choice is incorrect. Because some of the words in "D" were from the stimulus it was harder for me to recognize it as a random answer choice. This process helps me formulate a better prephrase for the question I missed and for the next time. It also helps me comprehend the test more. Understanding why the test makers thought I would fall for the answer choice in the first place usually helps me avoid it for the next time in cases where my prephrase is not as strong.
jessicamorehead
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Isn't "without" one of those words where whatever is after it is the necessary, and then you negate the sufficient side? So shouldn't the second conditional statement read "NOT grayish --> use filler"?? I'm confused how you made the second conditional statement. Also, I chose the correct answer C, but can someone explain why A and E are incorrect?
Adam Tyson
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You're correct, Jessica, and if you look again you will see that the second conditional claim in Claire's description is just the contrapositive of what you came up with:

Grayish :arrow: Filler

Filler :arrow: Grayish

These two statements are logically equivalent, and so they are completely interchangeable!

A is incorrect because the author does not need to assume anything about "certain kinds of paper". Try negating that statement - ALL kinds of paper can be made from recycled paper. Does that ruin the argument about needing more filler? Not at all! That conclusion is still based on the idea that whiteness is a requirement. The ability or lack of ability to make some paper from recycled paper is irrelevant to the white/gray issue.

E is incorrect because it, too, is irrelevant. What if the total amount of paper is not going to increase? Does that mean the white/gray issue is no longer an issue? Nope - our author could still be correct that for whatever kind or however much paper we are making, grayish paper will be unacceptable.

I hope that helps!
Adam M. Tyson
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