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Author Topic: 10 More Actual, Official LSAT PTs  (Read 1054 times)

nooyyllib

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10 More Actual, Official LSAT PTs
« on: March 02, 2009, 11:16:11 PM »
Hey all,

Because of my paranoia of running out of PTs after saving about 8 for the final push I went over all my incorrect questions from 10 more actual book (PT19-28) - looking at why the correct answer is correct and why the wrong was wrong.  From this I have 12 questions I'm stuck on and would greatly appreciate it (once again) if you guys can help me better understand them.  All of them are logical reasoning.

PT 21: section 2

#19: The components listed in the stimulus says "in order of decreasing abundance" in the atmosphere. I am confused about this because initially, I thought the stimulus was saying there was least methane in the atmosphere and the most nitrogen in the atmosphere.  But looking at the answer choice (C) I can tell that it was saying there was least nitrogen in the atmosphere and the most methane in the atmosphere - thus the assumption of methane vaporizing the easiest and carbon monoxide hardest.  But in this case, how can I surely figure out which order the stimulus is saying?

PT 22: section 2

#18: I understand why (B) is the answer because it only meets the originality while the influence is only minor therefore cannot be considered truly great.  However, I am not quite understanding why (C) is incorrect.  It says like the drumming practiced in Africa has tremendous originality and also profound impact on musicians everywhere, therefore it is great.  Please show me why (C) is incorrect.

#25: Is the sufficient condition being "indicted" and required condition "only if they are convicted"? I'm slightly confused.

PT 23: section 2

#25: I think the reasoning pattern is basically "this will only produce this result" - centrally planned allocation will result in at least 5% debt - (B) - pollution occurs only where there is a lot of cars.  I chose (D) originally.  But (D) is incorrect because of mistaken reversal? - being a famous rock star is a necessary condition to receive large regular loyalties - and owning their recording companies is just a side fact?

       section 3

#25: Can anyone put the stimulus in clear terms? Slightly confused.

PT 28: section 1

#19: I understand why the answer can be (A) but can an argument based on "belief" be considered a flaw?

#20: Is the answer (A) because investment decreasing is a completely different aspect from the causal condition given at the beginning of the stimulus? Because the stimulus clearly says "investment is not decreasing"? So, (A) which says "...investment is decreasing" is the answer? If this method is wrong please show me the right logic.


       section 3

#16: So, people think venereal disease caused Beethoven's deafness.  People during his time used mercury to treat VD so if they find mercury in his hair, the hypothesis is correct.  So, how does assuming (B) is correct?

Thanks a lot guys!

nooyyllib

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Re: 10 More Actual, Official LSAT PTs
« Reply #1 on: March 02, 2009, 11:18:09 PM »
*edit 8 questions.

zippyandzap

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Re: 10 More Actual, Official LSAT PTs
« Reply #2 on: March 02, 2009, 11:26:47 PM »
*edit 8 questions.
there's a modify button

nooyyllib

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Re: 10 More Actual, Official LSAT PTs
« Reply #3 on: March 04, 2009, 03:07:47 PM »
bump

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Re: 10 More Actual, Official LSAT PTs
« Reply #4 on: March 04, 2009, 06:52:44 PM »
I'll take on a couple of them.

PT 21 - 2/19

You did not misunderstand the meaning of the argument.  You totally misunderstood Choice C.  It sounds like you had an expectation of the assumption you expected the cr to fill and tried to force Choice C into that expectation rather than seeing it for what it says. 

In any argument there are numerous potential assumptions LSAC can choose from for the cr.  In this case, they did not go with the big picture assumption.  They choose a smaller one.  Since the conclusion lists the three components in order, there is an assumption there are no other elements in between.  That is all Choice C is saying and it is a necessary assumption of the argument (one of many).

PT 22 - 2/18

This time LSAC tricked you with words.  "Profound impact" does not necessarily mean influence.  Impact and influence are two different things (even though they both start with "I").  That is why Choice C is incorrect.

I'll do more later if nobody else does. 
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Re: 10 More Actual, Official LSAT PTs
« Reply #5 on: March 04, 2009, 08:22:18 PM »
#25: Is the sufficient condition being "indicted" and required condition "only if they are convicted"? I'm slightly confused.

PT 23: section 2

#25: I think the reasoning pattern is basically "this will only produce this result" - centrally planned allocation will result in at least 5% debt - (B) - pollution occurs only where there is a lot of cars.  I chose (D) originally.  But (D) is incorrect because of mistaken reversal? - being a famous rock star is a necessary condition to receive large regular loyalties - and owning their recording companies is just a side fact?       

PT 22 - 2/25

Students make this into a tougher question than it needs to be.  They think they know something they do not know and were not told (about the relationship between indictments and convictions); they think about the conditions in the premises and not the conclusion; and, most importantly, they fail to realize Choices A, C, D and E are just plain incorrect. 

In this argument, in the premises, indictment is a sufficient condition for resignation and conviction is a necessary condition for resignation.  However, for the conclusion they are both alleged to be sufficient conditions.  What does this mean?

First, it means this argument is baseless.  We know how many people think indictment is sufficient for resignation (50%).  We have no idea how many think conviction is sufficient for resignation.  (We know how many think it is necessary (35%) but we do not know how many think it is sufficient.  Remember, just because something is a necessary condition does not mean it is a sufficient condition).  So, this conclusion cannot be reached logically on these facts. 

So, what mistake did the person making the argument commit?  In the second half of the conclusion, what they claimed was a sufficient condition (believed they should resign “if convicted”), was treated as though it was a necessary condition (the one which their premise stated was true.)  In other words, if they had concluded “more people believe that elected officials should resign if indicted than believe they should resign only if convicted,” they would have a valid argument.  In their conclusion, they confused a sufficient condition for a required one.  Choice B.
 
As far as the other response options, Choice A is not a flaw.  That is done accurately all the time (like polling data).  I cannot imagine what ambiguity Choice C is claiming.  I think that is a trap answer for those who were confused by the argument and did not figure why they were confused.  Choice D is also not a problem.  As I wrote above, a valid conclusion could have been drawn about a specific belief based upon queries about two different beliefs if the conclusion was otherwise accurate.  Choice E is simply not true.  There is nothing self-contradictory about these premises.  One is a sufficient condition while the other is a necessary condition - two different things.


PT 23 - 2/25

Although many of the well-know commercial prep companies teach it this way, I think it is a mistake to take these things apart and try to match up components to find the correct response.  That is why these questions take students too much time and they hate them.  The easiest way to handle a parallel reasoning question is to look at the argument and determine its structure.  In this case:

All A (centrally planned) are Not B (efficient allocation of resources)
All C (debt < 5%) are B. 
Therefore
All A are Not C

Now, let’s look at the response options:

Choice A?  All A (mammals) are Not B (winged) because C are A and C are B.  First, let’s flip it around so it matches the direction of the initial argument.  All C are A; All C are B; therefore All A are Not B.  We can see this is clearly different.  (The second term in both premises is not the same as it is in the initial argument).  Strike it.

Choice B?  All A (rural districts) are Not B (polluted) because All B are C (a lot of cars) and All A are Not C.  Once we place this in the correct order to match the initial argument and flip around the two premises - All A are Not C; All B are C; therefore All A are Not B - we can see this is a perfect match (except of the fact what we labeled as B in the initial argument has been labeled as C in this argument and vice versa, but that is inconsequential.)  Mark it.

Choice C?  All A (ungulates) are B (herbivores).  Most B are Not C (people attackers).  This is different enough already.  Strike it.

Choice D?  All A who are B are C.  This is different enough already.  Strike it.

Choice E?  All A (fund managers) are B (knowers of inside traders).  All C are D (known to fund managers).  This is already different enough.  Strike it. 

In addition, it is okay if you did not want to go through the entirety of Choices A and B to see if they were correct on first glace.  It was sufficient to realize they were not obviously incorrect, keep them in play, then move on.  Choices C, D and E eliminate very quickly using this method.  Then you can go back to Choices A and B - knowing one of them is the correct response - and figure it out very quickly. 


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Re: 10 More Actual, Official LSAT PTs
« Reply #6 on: March 04, 2009, 09:10:18 PM »
PT 28 - 1/19

Q.  I understand why the answer can be (A) but can an argument based on "belief" be considered a flaw?

A.  I do not think you understand what is going on here.  You are incorrect about both things you have said.  First, it is not that Choice A can be an answer.  Choice A is the answer.  Plus, I can see you do not understand Choice A by your question.  Choice A is not saying the argument is incorrect merely because the argument is based on a belief. 

Look at the argument itself.  The premises tell us that something used to be believed to be true but there is a new school of though which does not believe that it is true.  That is all well and good.  But, then the problem with the argument arises.  The conclusion (“we inhabit a world full of irregular events , and in which there are no universal truths”) is a statement of fact.  Facts are never the results of beliefs.  That is the flaw.  Facts are facts.  Beliefs are beliefs.  If the conclusion stated a belief, there would be no problem with this argument.  So, to answer your question, no, an argument is not flawed merely because it is based on a belief.  However, it is flawed when a factual conclusion is reached and the only premises are beliefs.  That is what Choice A states.  You need to be aware of this and understand it.  LSAC tests this flaw all the time.  Nothing is true merely because people believe it is true. 


PT 28 - 1/20

Q. Is the answer (A) because investment decreasing is a completely different aspect from the causal condition given at the beginning of the stimulus? Because the stimulus clearly says "investment is not decreasing"? So, (A) which says "...investment is decreasing" is the answer? If this method is wrong please show me the right logic.

A.  No.  An “or” statement can never be false merely because one half of it is false.  Both components need to be false for the statement to be false.  So, while you are correct the second half is false (because it contradicts a stated fact) for the whole statement to be false the first part would also have to be false.  So, that is the issue you must deal with logically - must it be false that the economy is weak? 

Look at the argument this way:

If A (weak econ) then B (constant prices)
If A then C (unemployment rises)
C only if D (investment decreases) [same as if Not D then Not C]
Not D

Now, let’s think about whether A (weak economy) is necessarily false.  We know:

Not D

Therefore, we also know Not C (since C only if D)

If we know Not C then we know Not A (contrapositive of the second premise). 

So, we know Not D (from the final premise) and we know If Not D then Not A.  Therefore, both A and D cannot be true (both must be false) and this is the correct response. 
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Re: 10 More Actual, Official LSAT PTs
« Reply #7 on: March 04, 2009, 10:02:33 PM »

PT 28: section 3

#16: So, people think venereal disease caused Beethoven's deafness.  People during his time used mercury to treat VD so if they find mercury in his hair, the hypothesis is correct.  So, how does assuming (B) is correct?

With this question we have come full circle.  You have made the same mistake as in the first question you asked.  You have decided what assumption you are looking for (the grand, all-encompassing assumption) and tried to force the correct response to fit that mold.  That is a very backward way to handle assumption questions.  (It sounds like the Kaplan method).  You cannot do that.  Like I wrote about your first question, there are many assumptions in any given argument.  Identifying one and looking for it amongst the response options will not always work.  You have to look at each response option and determine whether it is an assumption of the argument or not.  Furthermore, in this case the question states it is looking for an argument upon which the argument depends.  That means without the assumption, the argument cannot be true.

So, what happens to this argument if we do not make the assumption claimed in Choice B?  That means all people ingested mercury.  Since all people did not have VD, then some people who did not have VD would still have mercury in their hair.  Then, if some people with mercury in their hair did not have VD, the fact that Beethoven did have mercury in his hair could not prove he had VD.  (And in this case, even though the argument has another fatal flaw, it does not change the fact of whether this assumption is or is not required for it).
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nooyyllib

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Re: 10 More Actual, Official LSAT PTs
« Reply #8 on: March 09, 2009, 12:04:53 PM »
thanks

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Re: 10 More Actual, Official LSAT PTs
« Reply #9 on: March 10, 2009, 12:48:36 AM »
PT22--2/18
Now we have a difficult choice between (B) and (C). This is a good time to discuss necessary and
sufficient pre-conditions. The passage states that the two elements are necessary before the work can be
truly great. But, just have these two necessary elements is not sufficient to make the work great. With that
in mind, look at (C) again. Note the use of the word enough, this implies that there need be no third
element in place to make a work truly great. I.e. these two are sufficient. The passage states the two
element are necessary, but doesn’t say they are sufficient. Answer (B) says that since this art lacks the
second element, it cannot be great, avoiding the issue about the possible existence of a third element. This
one was a tough call.