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(Assumption question) test 21, 2, #19

Beurre

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(Assumption question) test 21, 2, #19
« on: October 06, 2007, 02:52:25 PM »


Spectroscopic analysis has revealed  the existence of frozen nitrogen, methane, and carbon monoxide on the surface of Pluto. Such ices have a tendency to vaporize, producing an atmosphere. Since the proportion of any gas in such an atmosphere depends directly on how readily the corresponding ice vaporizes, astronomers have concluded that the components of Pluto's atmosphere are nitrogen, carbon monoxide, and methane, in order of decreasing abundance.

assumption?

a) there is no more frozen nitrogen on the surface of Pluto than there is either frozen carbon monoxide or methane.

b) until space probes reach pluto, direct analysis of the atmosphere is impossible
c) there is no frozen substance on the surface of Pluto that vaporizes more readily than methane but less readily than carbon monoxide.
d) nitrogen is found in the atmosphere of a planet only if nitrogen ice is found on the surface of that planet.

e) mixture of nitrogen, carbon monixide, and methane is characteristic of the substances from which solar system formed.


Beurre

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Re: (Assumption question) test 21, 2, #19
« Reply #1 on: October 07, 2007, 07:22:14 AM »
what's sufficient or necessary assumption question?? Oh I get it, sufficient -> justify conclusion, neccessary -> assumption. That's how LRB's taxonomy works...



at any rate,

The question stem: the astronomers' argument relies on which one of the following assumptions?

t L

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Re: (Assumption question) test 21, 2, #19
« Reply #2 on: October 07, 2007, 07:46:51 AM »
I remember doing this one and I believe that the answer is C.

On Assumption questions, you should really focus on the conclusion which is that "Pluto's atmosphere are nitrogen, carbon monoxide, and menthane, in order of descreasing abundance".  The evidence that we are given is that the proportion of any gas in such an atmosphere directly depends on how readily the corresponding ice vaporizes.  So the logical assumption missing between the conclusion and the premise is that nitrogen, carbon monoxide, and menthane readily vaporize in that order.  So you would look for that assumption in the answer choice.

A) Wrong.  Quantity isn't important.  How readily it vaporizes is what is important.

B) Irrevelant.  This is one of those answers you should look at and instantly throw out because it's so off the mark.

C) Correct answer.  If this were true (assumption negation technique), then the composition of the atmosphere would be nitrogen, carbon monoxide, mystery substance, and menthane.  That would make the authors conclusion false.  Notice that answer choice is a little different from what we are looking for, but it still works.

D) This answer could be tempting, but negate it and see what happens.  "Nitrogen could be found in the atmosphere of a planet even if nitrogen ice may not be found on the surface of that planet."  If that's true, does it really weaken the argument of the scientists? No.

E) Irrevelant.  This is another one of those answers that you should instantly throw out because it's so off the mark.


For Assumption questions, try to find the jump or gap in between the premises and conclusion.  If there is a gap, look for that gap to be an answer choice or something similar.  If there isn't a gap, then it's mostly likely going to be a defender assumption which protect that conclusion from outside information that could destroy it.

When going through the answer choices, throw out the completely irrelevant ones first.  At least two should be gone, but more likely three, then use the assumption negation technique on the remaining choices.

Beurre

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Re: (Assumption question) test 21, 2, #19
« Reply #3 on: October 07, 2007, 08:10:50 AM »
I remember doing this one and I believe that the answer is C.

On Assumption questions, you should really focus on the conclusion which is that "Pluto's atmosphere are nitrogen, carbon monoxide, and menthane, in order of descreasing abundance".  The evidence that we are given is that the proportion of any gas in such an atmosphere directly depends on how readily the corresponding ice vaporizes. So the logical assumption missing between the conclusion and the premise is that nitrogen, carbon monoxide, and menthane readily vaporize in that order. So you would look for that assumption in the answer choice.

A) Wrong.  Quantity isn't important.  How readily it vaporizes is what is important.

B) Irrevelant.  This is one of those answers you should look at and instantly throw out because it's so off the mark.

C) Correct answer.  If this were true (assumption negation technique), then the composition of the atmosphere would be nitrogen, carbon monoxide, mystery substance, and menthane.  That would make the authors conclusion false.  Notice that answer choice is a little different from what we are looking for, but it still works.

D) This answer could be tempting, but negate it and see what happens.  "Nitrogen could be found in the atmosphere of a planet even if nitrogen ice may not be found on the surface of that planet."  If that's true, does it really weaken the argument of the scientists? No.

E) Irrevelant.  This is another one of those answers that you should instantly throw out because it's so off the mark.


For Assumption questions, try to find the jump or gap in between the premises and conclusion.  If there is a gap, look for that gap to be an answer choice or something similar.  If there isn't a gap, then it's mostly likely going to be a defender assumption which protect that conclusion from outside information that could destroy it.

When going through the answer choices, throw out the completely irrelevant ones first.  At least two should be gone, but more likely three, then use the assumption negation technique on the remaining choices.



Thank you for showing me one by one; it makes sense to me that C is the right answer.

Thanks again.
 

Beurre

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Re: (Assumption question) test 21, 2, #19
« Reply #4 on: October 07, 2007, 06:27:39 PM »
Final ID,

yeah, I get your point.. Actually, this question was a bit more manageable for me than the other one I posted. Would you consider this easier than the other asumption quesiton?? I actually understand what makes C the right answer. In any case, the point about an assumption = what should be inherently necessary given the argument.

 

EarlCat

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Re: (Assumption question) test 21, 2, #19
« Reply #5 on: October 08, 2007, 10:40:13 AM »
but the question asks "relies on which ONE of the following assumptions." Since none of the others (ABDE) is possible, the question stem itself leads to a type of monocularity of vision. I don't like that.

I'll take Over-thinking the Question Stem for 500, Alex.

Re: (Assumption question) test 21, 2, #19
« Reply #6 on: October 09, 2007, 08:44:57 PM »
Sigh. All the logics you learned would not be of any use if you do not know how to put them into a comprehensible and plausable statement. LSAT isn't all that difficultly worded(except few triple Whoppers we often see, of course) It just requires you to understand and remember multiple facts and play around with them to deduce additional facts or assumptions.