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Q5 - Astronaut: Any moon, by definition,

by rsmorale Tue Jul 26, 2011 4:59 pm

Please critique my approach to this Sufficient Assumption question--


Premise: Any moon orbits some planet in a solar system
Conclusion: The moons in solar system S4 all orbit around Alpha

(A) Premise alludes to more than one moon.
(B) No mention of Alpha.
(C) If Alpha is the only planet in S4, then all the moons are forced to orbit around Alpha in order for the conclusion to be true. C is credited.
(D) Doesn't support conclusion ; could be true, but who cares?
(E) This is necessary, but not sufficient - correct? And the premises allude to more than one. This incorrectly lowers the degree level of the conclusion.
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Re: Q5 - Astronaut: Any moon, by definition,

by maryadkins Wed Jul 27, 2011 11:18 am

Good job! See below for some slightly different ways of analyzing the answer choices, but overall, well-done.

The premise is that if it's a moon, it orbits SOME planet in the solar system. The conclusion is that all the moons in one solar system (S4) orbit the same planet (Alpha). But we can only draw that conclusion if the planet Alpha is the only one in that solar system. Since all we've been told is that all moons have to orbit SOME planet in a SS, if there are any other planets in that SS, moons could be orbiting those. (C) eliminates this possibility.

(A) doesn't tell us why the moon, even if it's the only one, has to be orbiting Alpha and not some other planet.
(B) likewise doesn't give us a reason why Alpha is the planet being orbited--okay, they all orbit the same one, but is it Alpha?
(D) likewise doesn't give us a reason to conclude that Alpha is the planet all the moons are orbiting.
(E) is a necessary assumption--we need at least one moon to be orbiting Alpha--but we're looking for a sufficient assumption. The conclusion is that ALL the moons orbit Alpha.
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Re: Q5 - Astronaut: Any moon, by definition,

by WaltGrace1983 Wed Jan 15, 2014 6:34 pm

Wouldn't (E) be wrong basically because this doesn't answer whether or not Alpha is actually IN S4 or not? Maybe Alpha is in S3.
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Re: Q5 - Astronaut: Any moon, by definition,

by maryadkins Mon Jan 20, 2014 1:45 pm

WaltGrace1983 Wrote:Wouldn't (E) be wrong basically because this doesn't answer whether or not Alpha is actually IN S4 or not? Maybe Alpha is in S3.


Also true!
 
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Re: Q5 - Astronaut: Any moon, by definition,

by donghai819 Fri Jan 01, 2016 5:24 pm

Did this question one month ago and picked B. Now after going over Manhattan LR textbook conditional reasoning section, it's clear that C is provable by conditional logic.

Premise: moon --> orbit planet
Conclusion: moon in S4 --> orbit alpha

Assumption: planet in s4 --> planet asphala
If there is any planet in S4, then it is Alpha

Majority of easier conditional logic fall into this pattern:
Premise: A-->B
Conclusion: A-->C
Correct answer: B-->C, or ~C--> ~B
 
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Re: Q5 - Astronaut: Any moon, by definition,

by SANTHOSH KUMARK682 Fri Sep 15, 2017 6:34 am

Hi,

I initially chose C,

but tried negating the assumption.

~C => There could be some planets other than Alpha.
But those others planets can be without moon and still alpha can have all moons orbiting around it, so argument does not fall apart. So C can't be assumption.

Experts please clarify.