## Solar pond

##### This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 150
Joined: 08 Mar 2011
Thanked: 5 times
by finance » Wed May 18, 2011 2:55 am
champmag wrote:B and A.

The conclusion of the last paragraph states that the method used allows for an effective control of nuisance algae while leaving the ponds clean.

Any option that saya that algae nuisance is not yet over is the one that weakens the conclusion.
Op B says that the lateral movement of algae was not impaired i.e( in my opinion) algae were still floating in water, even though they were destroyed. I think this is better attck on the conclusion than Op C. Please correct me Atul, if I am wrong.

I thought exactly like you. B and A. Why can it not be B?

Newbie | Next Rank: 10 Posts
Posts: 4
Joined: 07 Jan 2011
by gmat11 » Wed May 18, 2011 3:35 am
Even i thought that the answers are B and A..cannot understand why B is wrong in Q1

GMAT Instructor
Posts: 905
Joined: 12 Sep 2010
Thanked: 378 times
Followed by:123 members
GMAT Score:760
by [email protected] » Wed May 18, 2011 3:39 am
gmat11 wrote:Even i thought that the answers are B and A..cannot understand why B is wrong in Q1
There's a reason why the answer choice mentions "lateral" - means side to side, not up and down. If the algae sank to the bottom of the pool, they no longer interfere with the absorption of light from the sun - the pool is transparent. In that case, they are free to move around laterally to their little algaic heart's content - the mission of cleaning the pool so that the waters are transparent has been accomplished.
Geva
Senior Instructor
Master GMAT
1-888-780-GMAT
https://www.mastergmat.com

Master | Next Rank: 500 Posts
Posts: 218
Joined: 24 Jul 2010
Thanked: 5 times
by cyrwr1 » Fri May 20, 2011 12:42 pm
This passage was all over the place and I also picked D for Q1, confusing all in all.

Senior | Next Rank: 100 Posts
Posts: 80
Joined: 09 Jan 2011
Thanked: 4 times
Followed by:5 members
by powerpuff » Sat May 21, 2011 9:42 am
cyrwr1 wrote:This passage was all over the place and I also picked D for Q1, confusing all in all.
Same here. I also picked D for the first question

Legendary Member
Posts: 1112
Joined: 26 Feb 2011
Thanked: 77 times
Followed by:49 members
by atulmangal » Sat May 21, 2011 9:57 am
Guys,

OA is C and A

Legendary Member
Posts: 1112
Joined: 26 Feb 2011
Thanked: 77 times
Followed by:49 members
by atulmangal » Sat May 21, 2011 10:01 am
finance wrote:
champmag wrote:B and A.

The conclusion of the last paragraph states that the method used allows for an effective control of nuisance algae while leaving the ponds clean.

Any option that saya that algae nuisance is not yet over is the one that weakens the conclusion.
Op B says that the lateral movement of algae was not impaired i.e( in my opinion) algae were still floating in water, even though they were destroyed. I think this is better attck on the conclusion than Op C. Please correct me Atul, if I am wrong.

I thought exactly like you. B and A. Why can it not be B?
Hey guys even i thought exactly the same, wonder we all three have same set of thinking and picked up the wrong answer...

Legendary Member
Posts: 1112
Joined: 26 Feb 2011
Thanked: 77 times
Followed by:49 members
by atulmangal » Sat May 21, 2011 10:10 am
[email protected] wrote:The main thing with Q1 is to first clarify for yourself what are you trying to weaken - what is the conclusion drawn from the experiment. This is actually not different from any regular weaken CR question - find the premises and conclusion. This is the last sentence:

"This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use. "

So there are actually two conclusions that we can weaken: that the method words, and that it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph). I think that C is the right answer because it weakens the second conclusion: microorganisms that kill algae can be considered a contaminating algicide, indicating that the method, while effective, is not clean.

Call this a supporting point in addition to the comments above. At the end of the day, the answer is C because it is not A, B, D or E, i.e. b elimination.
Hi Geva, u said that Op C is good because its undermines this conclusion
it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph
But in the passage no where mentioned that microorganisms affect the environment. As we can not apply our general knowledge in such questions so we can't think in that way at all....why i drop Op C is because if Op C is the answer then Op D can also be the answer. My opinion is Op C is suggesting a different way suggesting that Algae was not killed because of the method prescribed in passage but something else cause...i mean this is the situation which we generally deal in CR argument...

if A cause B, then to weaken prove

A does not causes B or X causes B

so Op C is suggesting that X causes B not A causes B...

That's okaay, Op C can be the answer then why no Op D tooo....Op D also showing the same thing????

Please clear...also if u find enough time one more time please elaborate the ans of this question...i checked on other forums too and many guys are struggling with this question. I got ur point why Op B which i picked is wrong...thats okay!!!

Thanks

GMAT Instructor
Posts: 905
Joined: 12 Sep 2010
Thanked: 378 times
Followed by:123 members
GMAT Score:760
by [email protected] » Sat May 21, 2011 12:26 pm
atulmangal wrote:
[email protected] wrote:The main thing with Q1 is to first clarify for yourself what are you trying to weaken - what is the conclusion drawn from the experiment. This is actually not different from any regular weaken CR question - find the premises and conclusion. This is the last sentence:

"This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use. "

So there are actually two conclusions that we can weaken: that the method words, and that it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph). I think that C is the right answer because it weakens the second conclusion: microorganisms that kill algae can be considered a contaminating algicide, indicating that the method, while effective, is not clean.

Call this a supporting point in addition to the comments above. At the end of the day, the answer is C because it is not A, B, D or E, i.e. b elimination.
Hi Geva, u said that Op C is good because its undermines this conclusion
it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph
But in the passage no where mentioned that microorganisms affect the environment. As we can not apply our general knowledge in such questions so we can't think in that way at all....why i drop Op C is because if Op C is the answer then Op D can also be the answer. My opinion is Op C is suggesting a different way suggesting that Algae was not killed because of the method prescribed in passage but something else cause...i mean this is the situation which we generally deal in CR argument...

if A cause B, then to weaken prove

A does not causes B or X causes B

so Op C is suggesting that X causes B not A causes B...

That's okaay, Op C can be the answer then why no Op D tooo....Op D also showing the same thing????

Please clear...also if u find enough time one more time please elaborate the ans of this question...i checked on other forums too and many guys are struggling with this question. I got ur point why Op B which i picked is wrong...thats okay!!!

Thanks
I agree that we can't use outside info, but that's irrelevant - my knowledge of environmental microbiology is extremely limited (basically, these passages teach me all I know on the subject ). The only reason I suspect that microorganisms are a possible contaminant is because the passage cites algicide (=the killing of algae - the suffix cide means kill) in paragraph 3, and then discounts the method as a possible contamination risk. I am drawing an analogy here that any outside agent that kills algae is a possible contaminator, including microorganisms. Thus, my knowledge of the subject is based on what the passage tells me, not any outside expertise.

You're right that that analogy is unsupported in the passage, but that is the only thing that puts C ahead of the others.
Why D is wrong: I think you're blindly applying a method instead of applying common sense. If the conclusion we were here to weaken were "the algae were killed by the heat in the deep regions", then D would be 100% the answer, as it poses an alternative explanation to the conclusion. However, the method of killing the algae is not the conclusion, but actually given as a premise - it's part of the description of the method: salinity changes-->algae absorb water-->algae sink-->algae killed by heat.

The conclusion takes for granted that the method kills algae, and takes it to the next level - that this killing method is both effective in clearing the pool, and is cleaner (no contamination risk) than previously proposed methods. THIS is the conclusion we are here to weaken, and to do that we need to do one of the following - either prove that the method isn't effective in cleaning the pool (for example, an answer choice saying that the bodies of the algae float back upwards after they are killed, so the pool is still scummy), or prove that the method, while effective, is not clean.

C and D do the same thing in terms of bringing an alternative cause of death, but C's advantage over D is that it ALSO produces a contaminant - the outside microorganisms brought in by the water used to change the salinity. So C challenges the second part of the conclusion (that the method is clean), and is thus better than the other options.

Put it this way - If C had introduced some other explanation for killing the algae that doesn't introduce an outside element (for example - the algae that sank to the bottom of the pool were forced to read GMAT RC passages until they died of boredom), then it would indeed have no advantage over D. In that case, this question would have NO right answer.
Geva
Senior Instructor
Master GMAT
1-888-780-GMAT
https://www.mastergmat.com

Legendary Member
Posts: 1112
Joined: 26 Feb 2011
Thanked: 77 times
Followed by:49 members
by atulmangal » Sat May 28, 2011 7:25 am
[email protected]erGMAT wrote:
atulmangal wrote:
[email protected] wrote:The main thing with Q1 is to first clarify for yourself what are you trying to weaken - what is the conclusion drawn from the experiment. This is actually not different from any regular weaken CR question - find the premises and conclusion. This is the last sentence:

"This method allows for effective control of nuisance algae while leaving solar ponds as one of the cleanest technologies providing energy for human use. "

So there are actually two conclusions that we can weaken: that the method words, and that it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph). I think that C is the right answer because it weakens the second conclusion: microorganisms that kill algae can be considered a contaminating algicide, indicating that the method, while effective, is not clean.

Call this a supporting point in addition to the comments above. At the end of the day, the answer is C because it is not A, B, D or E, i.e. b elimination.
Hi Geva, u said that Op C is good because its undermines this conclusion
it's still clean (as opposed to the algicide method discounted as too messy in the third paragraph
But in the passage no where mentioned that microorganisms affect the environment. As we can not apply our general knowledge in such questions so we can't think in that way at all....why i drop Op C is because if Op C is the answer then Op D can also be the answer. My opinion is Op C is suggesting a different way suggesting that Algae was not killed because of the method prescribed in passage but something else cause...i mean this is the situation which we generally deal in CR argument...

if A cause B, then to weaken prove

A does not causes B or X causes B

so Op C is suggesting that X causes B not A causes B...

That's okaay, Op C can be the answer then why no Op D tooo....Op D also showing the same thing????

Please clear...also if u find enough time one more time please elaborate the ans of this question...i checked on other forums too and many guys are struggling with this question. I got ur point why Op B which i picked is wrong...thats okay!!!

Thanks
I agree that we can't use outside info, but that's irrelevant - my knowledge of environmental microbiology is extremely limited (basically, these passages teach me all I know on the subject ). The only reason I suspect that microorganisms are a possible contaminant is because the passage cites algicide (=the killing of algae - the suffix cide means kill) in paragraph 3, and then discounts the method as a possible contamination risk. I am drawing an analogy here that any outside agent that kills algae is a possible contaminator, including microorganisms. Thus, my knowledge of the subject is based on what the passage tells me, not any outside expertise.

You're right that that analogy is unsupported in the passage, but that is the only thing that puts C ahead of the others.
Why D is wrong: I think you're blindly applying a method instead of applying common sense. If the conclusion we were here to weaken were "the algae were killed by the heat in the deep regions", then D would be 100% the answer, as it poses an alternative explanation to the conclusion. However, the method of killing the algae is not the conclusion, but actually given as a premise - it's part of the description of the method: salinity changes-->algae absorb water-->algae sink-->algae killed by heat.

The conclusion takes for granted that the method kills algae, and takes it to the next level - that this killing method is both effective in clearing the pool, and is cleaner (no contamination risk) than previously proposed methods. THIS is the conclusion we are here to weaken, and to do that we need to do one of the following - either prove that the method isn't effective in cleaning the pool (for example, an answer choice saying that the bodies of the algae float back upwards after they are killed, so the pool is still scummy), or prove that the method, while effective, is not clean.

C and D do the same thing in terms of bringing an alternative cause of death, but C's advantage over D is that it ALSO produces a contaminant - the outside microorganisms brought in by the water used to change the salinity. So C challenges the second part of the conclusion (that the method is clean), and is thus better than the other options.

Put it this way - If C had introduced some other explanation for killing the algae that doesn't introduce an outside element (for example - the algae that sank to the bottom of the pool were forced to read GMAT RC passages until they died of boredom), then it would indeed have no advantage over D. In that case, this question would have NO right answer.
Thanks Geva...this post cleared my confusion

Master | Next Rank: 500 Posts
Posts: 439
Joined: 09 Aug 2008
Location: India
Thanked: 34 times
Followed by:28 members
by sivaelectric » Sat May 28, 2011 10:32 pm
IMO C and A. and thanks for the explanation.
If I am wrong correct me , If my post helped let me know by clicking the Thanks button .

Chitra Sivasankar Arunagiri

Junior | Next Rank: 30 Posts
Posts: 26
Joined: 22 May 2014

### Solar pond

by jabhatta » Fri Mar 02, 2018 4:57 pm
The answer for Q2 is A. The passage begins by telling us about solar ponds and the opportunity they present to generate elctrcity. The rest of the passage deals with the algae problem and the proposed methods for solving it. A is the answer choice that best and most comprehensively describes the various components of the passage.[/quote]

Hi for Q2 - why is D not the correct response