Logical Reasoning explanation for question needed

TLSNinja
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Joined: Fri Sep 21, 2012 1:20 pm

Logical Reasoning explanation for question needed

Postby TLSNinja » Fri Sep 21, 2012 1:37 pm

Hi TLS'ers

I'm new to the forum and am currently self prepping!

On the June 2009 lSAT, section 2 (LR), question # 10:

I was stuck choosing between answer B and E. The correct answer is B. I am not sure why.

I picked E because B said that farming practices introduced "for the sake of maximizing profits" when it seemed like the stimulus was arguing that we introduce better farming practices for the animals sake and we get a byproduct of higher profits.

Could you eliminate E by the word "key" which could be classified as too extreme in the sense that the stimulus never creates any type of hierarchy and says which method is the primary, principal, or best way to do something?


#16 LR same section

I was able to eliminate all the answers but A and B since I knew that "it fails to live up to its billing" was the main conclusion. But, I was unsure if there was a subsidiary conclusion that was also present.

My question is simply: how do you tell if a sub conclusion is also present? Does it almost always/always have some sort of conclusion keyword that identifies it? Like "after all?"

#19 LR same section

I was able to diagram the stimulus as follows: Premise: W - > C -> M ; Conclusion not M -> not W.

I was able to properly diagram all of the answer choices as well.

I skimmed over C, the right answer, because it was in this form:

Premise: S -> M - > C
Conclusion: S -> C

[If it was Not C -> Not S I would have seen it right away.]

Is this equivalent to the stimulus answer by taking the contrapositive of the conclusion? When encountering parallel reasoning questions in general do I need to be especially aware of contrapositives?

If yes, could valid answers have a contrapositive of the premise and conclusion format of the stimulus?

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BlaqBella
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Joined: Fri Jan 28, 2011 9:41 am

Re: Logical Reasoning explanation for question needed

Postby BlaqBella » Fri Sep 21, 2012 2:08 pm

TLSNinja wrote:#19 LR same section

I was able to diagram the stimulus as follows: Premise: W - > C -> M ; Conclusion not M -> not W.

I was able to properly diagram all of the answer choices as well.

I skimmed over C, the right answer, because it was in this form:

Premise: S -> M - > C
Conclusion: S -> C

[If it was Not C -> Not S I would have seen it right away.]

Is this equivalent to the stimulus answer by taking the contrapositive of the conclusion? When encountering parallel reasoning questions in general do I need to be especially aware of contrapositives?


Conclusion for C is actually: Not C --> Not S

TLSNinja wrote:If yes, could valid answers have a contrapositive of the premise and conclusion format of the stimulus?


Yes, it can, but not in this instance. The conclusion in the correct answer choice must match the similar direction of the conclusion in the stimulus.

TLSNinja
Posts: 6
Joined: Fri Sep 21, 2012 1:20 pm

Re: Logical Reasoning explanation for question needed

Postby TLSNinja » Fri Sep 21, 2012 4:50 pm

Usually when I do logic questions with the word "unless" I draw an arrow through the word unless and then negate the sufficient condition.

Is it better to just replace "unless" with "if not" ?




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