2016 verbal review--images from ground-based telescopes

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allenh: Newbie | Next Rank: 10 Posts; Posts: 5; Joined: Sat Jul 25, 2015 1:51 am; Thanked: 1 times

by allenh » Tue Sep 15, 2015 5:42 pm

Hello,

The question is attached to this post.

I am extremely baffled by this question.

The OA is E

And I chose B

because I believe that only the answer choice that relates to the ground-based telescopes is right one. And OA DOES NOT mention anything about ground-based telescope, how do we know it has more light-gathering capacity than space telescopes? How do we tackle this in the real GMAT exam?

I would be so thrilled if I could have some insight from the experts.

Cheers,
Allen

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Source: Beat The GMAT — Critical Reasoning | Tue Sep 15, 2015 5:42 pm

GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Wed Sep 16, 2015 2:46 am

Premises: Images from ground-based telescopes are invariably distorted. Space telescopes provide superbly detailed images.
Conclusion: Ground-based telescopes will soon become obsolete.

One assumption is that ground-based telescopes do not provide some benefit that cannot be provided by space telescopes.
To weaken the conclusion, the correct answer will attack this assumption.
E: Detailed spectral analyses require more light-gathering capacity than space telescopes can provide.
Since space telescopes cannot provide the light-gathering capacity required for detailed spectral analyses, astronomers will continue to need NON-SPACE telescopes -- in other words, GROUND-BASED telescopes -- weakening the conclusion that ground-based telescopes will soon become obsolete.

The correct answer is E.

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jain2016: Master | Next Rank: 500 Posts; Posts: 313; Joined: Tue Oct 13, 2015 7:01 am; Thanked: 2 times

by jain2016 » Sat Mar 05, 2016 10:28 pm

Hi GMATGuruNY ,

Can you please explain option B. whats wrong in this option?

Many thanks in advance.

SJ

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GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Sat Mar 05, 2016 11:11 pm

jain2016 wrote:Hi GMATGuruNY ,

Can you please explain option B. whats wrong in this option?

Many thanks in advance.

SJ

B: Ground-based telescopes located on mountain summits are not subject to the kinds of atmospheric distortion which, at low altitudes, make stars appear to twinkle.
This option attempts to weaken the PREMISE that images from ground-based telescopes are invariably distorted by the Earth's atmosphere.
A premise is a FACT; it cannot be weakened..
Eliminate B.

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RBBmba@2014: Legendary Member; Posts: 944; Joined: Wed May 30, 2012 8:21 amFollowed by: 5 members; Thanked: 8 times

by RBBmba@2014 » Tue May 10, 2016 4:54 am

GMATGuruNY wrote:Premises: Images from ground-based telescopes are invariably distorted. Space telescopes provide superbly detailed images.
Conclusion: Ground-based telescopes will soon become obsolete.

One assumption is that ground-based telescopes do not provide some benefit that cannot be provided by space telescopes.
To weaken the conclusion, the correct answer will attack this assumption.
E: Detailed spectral analyses require more light-gathering capacity than space telescopes can provide.
Since space telescopes cannot provide the light-gathering capacity required for detailed spectral analyses, astronomers will continue to need NON-SPACE telescopes -- in other words, GROUND-BASED telescopes -- weakening the conclusion that ground-based telescopes will soon become obsolete.

The correct answer is E.

It seems to me that this option E is considered OA through some sort of brute force -- I don't get the LOGIC behind E to be OA, except GMAC says "it's the OA" (and perhaps other options have CLEAR ERRORs).

To WEAKEN the CONCLUSION that ground-based telescopes will soon become obsolete for advanced astronomical research purposes, we need to find some sort of EVIDENCE indicating that there is AT LEAST one SIGNIFICANT advantage of ground-based telescopes over Space telescopes. But the OA provides a disadvantage of Space telescopes, without clearly mentioning whether ground-based telescopes can overcome this constraint or not!

So, don't understand how the Option E becomes the OA ? Please help.

P.S: What is the issue with A ?
Is it because A talks about one specific ground-based telescope and one specific Space telescope, whereas the ARGUMENT is about the overall ground-based telescopes and Space telescopes in GENERAL.

Could you please clarify ?

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DavidG@VeritasPrep: Legendary Member; Posts: 2663; Joined: Wed Jan 14, 2015 8:25 amFollowed by: 128 members; Location: Boston, MA; Thanked: 1153 times; GMAT Score:770

by DavidG@VeritasPrep » Wed Jun 01, 2016 8:09 am

To WEAKEN the CONCLUSION that ground-based telescopes will soon become obsolete for advanced astronomical research purposes, we need to find some sort of EVIDENCE indicating that there is AT LEAST one SIGNIFICANT advantage of ground-based telescopes over Space telescopes. But the OA provides a disadvantage of Space telescopes, without clearly mentioning whether ground-based telescopes can overcome this constraint or not!

It might be helpful to generalize the argument this way:

Technology A (currently in use) is mediocre. Technology B is, hypothetically, much better, because it does 'x.' Therefore Technology A will be phased out soon.

If it's the case that Technology B has some fatal flaw that prevents it from doing 'x,' the argument is weakened. Remember that Technology A, whatever its flaws, is currently in use. It simply doesn't make sense to argue that a mediocre tool (Technology A) will be replaced by one that, because of some fatal flaw, has no discernible advantages (Technology B).

Put another way, yes, it's possible that A will eventually be phased out because of its flaws, but it won't be because B is so great, which is, in essence, what the argument asserts.

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RBBmba@2014: Legendary Member; Posts: 944; Joined: Wed May 30, 2012 8:21 amFollowed by: 5 members; Thanked: 8 times

by RBBmba@2014 » Fri Jun 03, 2016 3:55 am

DavidG@VeritasPrep wrote:
To WEAKEN the CONCLUSION that ground-based telescopes will soon become obsolete for advanced astronomical research purposes, we need to find some sort of EVIDENCE indicating that there is AT LEAST one SIGNIFICANT advantage of ground-based telescopes over Space telescopes. But the OA provides a disadvantage of Space telescopes, without clearly mentioning whether ground-based telescopes can overcome this constraint or not!

It might be helpful to generalize the argument this way:

Technology A (currently in use) is mediocre. Technology B is, hypothetically, much better, because it does 'x.' Therefore Technology A will be phased out soon.

If it's the case that Technology B has some fatal flaw that prevents it from doing 'x,' the argument is weakened. Remember that Technology A, whatever its flaws, is currently in use. It simply doesn't make sense to argue that a mediocre tool (Technology A) will be replaced by one that, because of some fatal flaw, has no discernible advantages (Technology B).

Put another way, yes, it's possible that A will eventually be phased out because of its flaws, but it won't be because B is so great, which is, in essence, what the argument asserts.

@Dave - Don't get this clearly! Could you please elaborate in any way ?

And please let me know whether my following analysis of A is correct or not ?

Issue with A:
I think, A is wrong because A talks about one specific ground-based telescope and one specific Space telescope, whereas the ARGUMENT is about the overall Ground-based telescopes and Space telescopes in GENERAL.

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by GMATGuruNY » Sun Jun 05, 2016 3:10 am

RBBmba@2014 wrote:[I don't get the LOGIC behind E to be OA, except GMAC says "it's the OA" (and perhaps other options have CLEAR ERRORs).

To WEAKEN the CONCLUSION that ground-based telescopes will soon become obsolete for advanced astronomical research purposes, we need to find some sort of EVIDENCE indicating that there is AT LEAST one SIGNIFICANT advantage of ground-based telescopes over Space telescopes. But the OA provides a disadvantage of Space telescopes, without clearly mentioning whether ground-based telescopes can overcome this constraint or not!

So, don't understand how the Option E becomes the OA ? Please help.

OA: Detailed spectral analyses, upon which astronomers rely for determining the chemical composition and evolutionary history of stars, require telescopes with more light-gathering capacity than space telescopes can provide.
Since astronomers RELY UPON detailed spectral analyses, they must currently be able to OBTAIN detailed spectral analyses.
Since detailed spectral analyses require telescopes with more light-gathering capacity than space telescopes can provide, it must be true that detailed spectral analyses require telescopes that are NOT space-based.
In other words:
Detailed spectral analyses require telescopes that are GROUND-BASED.
Implication:
To obtain the detailed spectral analyses upon which they rely, astronomers must currently be using -- and must CONTINUE TO USE -- ground-based telescopes, weakening the conclusion that ground-based telescopes will become obsolete.

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info2: Junior | Next Rank: 30 Posts; Posts: 13; Joined: Tue Jun 07, 2016 10:12 am; Thanked: 1 times

by info2 » Thu Jun 09, 2016 11:28 pm

GMATGuruNY wrote:
RBBmba@2014 wrote:[I don't get the LOGIC behind E to be OA, except GMAC says "it's the OA" (and perhaps other options have CLEAR ERRORs).

To WEAKEN the CONCLUSION that ground-based telescopes will soon become obsolete for advanced astronomical research purposes, we need to find some sort of EVIDENCE indicating that there is AT LEAST one SIGNIFICANT advantage of ground-based telescopes over Space telescopes. But the OA provides a disadvantage of Space telescopes, without clearly mentioning whether ground-based telescopes can overcome this constraint or not!

So, don't understand how the Option E becomes the OA ? Please help.
OA: Detailed spectral analyses, upon which astronomers rely for determining the chemical composition and evolutionary history of stars, require telescopes with more light-gathering capacity than space telescopes can provide.
Since astronomers RELY UPON detailed spectral analyses, they must currently be able to OBTAIN detailed spectral analyses.
Since detailed spectral analyses require telescopes with more light-gathering capacity than space telescopes can provide, it must be true that detailed spectral analyses require telescopes that are NOT space-based.
In other words:
Detailed spectral analyses require telescopes that are GROUND-BASED.
Implication:
To obtain the detailed spectral analyses upon which they rely, astronomers must currently be using -- and must CONTINUE TO USE -- ground-based telescopes, weakening the conclusion that ground-based telescopes will become obsolete.

Hi Mitch

Option D is also wrong because it weakens the premise as well. Right?

Thanks

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GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Fri Jun 10, 2016 3:35 am

info2 wrote: Hi Mitch

Option D is also wrong because it weakens the premise as well. Right?

Thanks

Correct!
D: When large-aperture telescopes are located at high altitudes near the equator, they permit the best Earth-based observations of the center of the Milky Way Galaxy, a prime target of astronomical research.
Like B, this option attempts to weaken the PREMISE that images from ground-based telescopes are invariably distorted by the Earth's atmosphere.
A premise is a FACT; it cannot be weakened..
Eliminate D.

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RBBmba@2014: Legendary Member; Posts: 944; Joined: Wed May 30, 2012 8:21 amFollowed by: 5 members; Thanked: 8 times

by RBBmba@2014 » Tue Jun 21, 2016 3:58 am

GMATGuruNY wrote: OA: Detailed spectral analyses, upon which astronomers rely for determining the chemical composition and evolutionary history of stars, require telescopes with more light-gathering capacity than space telescopes can provide.
Since astronomers RELY UPON detailed spectral analyses, they must currently be able to OBTAIN detailed spectral analyses.
Since detailed spectral analyses require telescopes with more light-gathering capacity than space telescopes can provide, it must be true that detailed spectral analyses require telescopes that are NOT space-based.
In other words:
Detailed spectral analyses require telescopes that are GROUND-BASED.
Implication:
To obtain the detailed spectral analyses upon which they rely, astronomers must currently be using -- and must CONTINUE TO USE -- ground-based telescopes, weakening the conclusion that ground-based telescopes will become obsolete.

Hi GMATGuruNY,
Got you here...Just a quick confirmation required.

So,here it's essentially meant that as there could be either SPACE-BASED or GROUND-BASED telescopes ONLY, therefore if it's NOT SPACE-BASED then it has to be GROUND-BASED, even if there is NO EXPLICIT mention of the latter.

Did I get this right ?

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GMATGuruNY: GMAT Instructor; Posts: 15539; Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members; Location: New York, NY; Thanked: 13060 times; GMAT Score:790

by GMATGuruNY » Tue Jun 21, 2016 4:47 am

RBBmba@2014 wrote: Hi GMATGuruNY,
Got you here...Just a quick confirmation required.

So,here it's essentially meant that as there could be either SPACE-BASED or GROUND-BASED telescopes ONLY, therefore if it's NOT SPACE-BASED then it has to be GROUND-BASED, even if there is NO EXPLICIT mention of the latter.

Did I get this right ?

Correct.
Just as an integer that is NOT EVEN must be ODD, so a telescope that is NOT SPACE-BASED must be GROUND-BASED.
This sort of logic -- common sense, really -- does not need to be stated explicitly.

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RBBmba@2014: Legendary Member; Posts: 944; Joined: Wed May 30, 2012 8:21 amFollowed by: 5 members; Thanked: 8 times

by RBBmba@2014 » Tue Jun 21, 2016 4:53 am

@Verbal Experts - Can you please let me know whether my following analysis is correct in eliminating Option A & D ?

As for A: Issue seems that A talks about one specific ground-based telescope and one specific Space telescope, whereas the ARGUMENT is about the overall Ground-based telescopes and Space telescopes in GENERAL. Right ?

As for D: It seems to be NOT in the SCOPE of this ARGUMENT. "Large-aperture telescopes" - this is NOT mentioned anywhere in the ARGUMENT, I guess! Thoughts ?

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by MartyMurray » Mon Sep 05, 2016 3:05 am

RBBmba@2014 wrote:@Verbal Experts - Can you please let me know whether my following analysis is correct in eliminating Option A & D ?

As for A: Issue seems that A talks about one specific ground-based telescope and one specific Space telescope, whereas the ARGUMENT is about the overall Ground-based telescopes and Space telescopes in GENERAL. Right ?

Yes, and also, the fact that a space based telescope is behind schedule and over budget does not change the fact that it is better for getting detailed images than a ground based telescope is. So even if all space based telescopes were behind schedule and over budget, ground based telescopes could still become obsolete.

As for D: It seems to be NOT in the SCOPE of this ARGUMENT. "Large-aperture telescopes" - this is NOT mentioned anywhere in the ARGUMENT, I guess! Thoughts ?

That reason for eliminating D is too simplistic. Something not mentioned in the argument could be new information that weakens the argument. For instance this answer choice could have said that using large aperture telescopes located high on mountains is the best method among all available methods for getting images of the Milky Way, which would indicate that ground based telescopes are in some cases more effective than space based telescopes and so will not become obsolete.

To soundly eliminate an answer choice, really you have to show logically why it does not answer the question. In this case there is a clear logical reason why the answer choice does not affect the argument.

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RBBmba@2014: Legendary Member; Posts: 944; Joined: Wed May 30, 2012 8:21 amFollowed by: 5 members; Thanked: 8 times

by RBBmba@2014 » Mon Sep 05, 2016 10:38 pm

Thanks Marty for clarifying!

Could you please shed some light on the followings:

1. 2016-gmat-official-guide-weaken-q

2. difficult-to-approach-easy-task-hard-task-cr

Look forward to your thoughts. Much thanks in advance!

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