I concur with you that E is the answer

The key words are " open land" which, if correctecly understood, is land without many dwellers.
E: population of country Y is more scattering than that of country X --> it's more difficult to find "open land" in Y than in X --> the proposal to build wind farm in Y weakened.

But, then why there's a premise about the population density of the countries? ..

B seems a contender but since we don't have information about the area of the two countries' territories, we can't conclude anything

Pop density is higher in Cx than Cy.

E states that ALL pop of Cx is concentrated in a small part. So the density of pop is high AND can also mean that Cx has more open land than Cy.

I go for E

This is C.

X's population is denser. Thus, Wind farms should be built in Y.

A: Irrelevant
B: This is tempting but doesn't really explain why the mill's should not be built in Y. This requires us to make additional assumptions about greater population.
D: Doesn't weaken, both have the same land mass.

E. Says that population is very dense in one spot for X, but Y is spread out.
Just think of any state with a mega-major city: Illinois . Has Chicago and... thats about it. Chicago contains the majority of the population of Illinois. Now lets compare to say Ohio. Ohio has several major cities, but nothing compared to Chicago. And Ohio's pop is about equal but spread out. Assuming both have same land mass, its easy to see why Ohio would be a worse place to put wind mills.


Now judging from your comments, I can see that E is probably not the answer.

So I say C. The argument assumes that electricity will be purchased outside of Y. I thought this might be something that COULD weaken the argument, but this doesn't really follow the premises as E does. E perfectly explains why its not a good idea to put the mills in Y.

However, we must remember that when weakening the argument, we have to look for two types of choices: one that produces a piece of weakening evidence or one that exposes a faulty assumption.

The argument assumes that both countries will share electricity. This is why choice C is correct.


However, come test day Id still say E. Both are plausible. I guess E just requires us to assume that sparse population means worse for windmilss. This is a very iffy CR if you ask me.


Whoops made an error, fixed it in my reasoning for E with the above example of Ohio and Illinois.

Should be B.

(1) Total population of country B is substantial higher than that of A.
(2) Population density of country B is substantial lower than that of A.

It means population is spread out in country B, so not much "open land" may be available for wind farms.

A,C and D out of scope.
B - only population without the land area will not give any conclusion.
E is the answer.

E. this is clearly E cuz "wind farms need spacious land which is available in x and not in y. so x is better suited for the wind farms.

Thanks, quite a stimulating discussion. OA is E.

After POE B & E are the contenders.B will not undermine the Conclusion,E does.Therefore E is Answer

Wind farms, which generate electricity using arrays of thousands of wind-powered turbines, require vast expanses of open land. County X and County Y have similar terrain, but the population density of County X is significantly higher than that of County Y. Therefore, a wind farm proposed for one of the two counties should be built in County Y rather than in County X.

Type - weaken
Boil it down - a wind farm proposed for one of the two counties should be built in County Y rather than in County X.
- How big is each country -If the country Y is very small , then it might not have sufficient vast expanses of open land .
- How is the population distributed ?

A. County X and County Y are adjacent to each other, and both are located in the windiest area of the state.- Irrelevant
B. The total population of County Y is substantially greater than that of County X. - Irrelevant
C. Some of the electricity generated by wind farms in County Y would be purchased by users outside the county. - Irrelevant
D. Wind farms require more land per unit of electricity generated than does any other type of electrical-generation facility.- Irrelevant
E. Nearly all of County X’s population is concentrated in a small part of the county, while County Y’s population is spread evenly throughout the country. - Correct - if this is true , then there will be expanses of open land available in county X
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GMATNinja
VeritasPrepKarishma
GMATNinjaTwo


I was stuck between C/ E

Conclusion: A wind farm must be built for country Y rather than X

Why author says so: Because population density ie people living in per square unit area of land is more in X than in Y
Say X has 100 m2 square of area and 50 people are living in it
then Y has 45 people living in same area.

So more people means more DEMAND for electricity and hence wind farms should be built in X

How can I weaken this:
a. By showing that building a wind farm in Y would be more efficient than in X
b. Suggesting other reason than population density for wind farm to be built in X



If electricity produced in Y would be purchased by users OUTSIDE the country then Y would eventually fall electricity deficient. Hence building a wind farm to cover that deficient shall be a good option to cover that deficit.




If more people are concentrated in one particular zone, then it means the remaining portion of vacant land could be used for wind farms expansion. X has definitely more free land than Y as per this option, hence is correct choice.
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Premises:
Wind farms need vast expanses of open land.
Population density (people/sq mile) of X is higher than Y. (This means X may have 1000 people and 10 sq mile area giving a density of 100 while Y may have 2000 people but 40 sq mile area giving a density of 50)
A wind farm has to be made in one of the two counties.

Conclusion:
Make it in Y

We need to weaken the argument.

A. County X and County Y are adjacent to each other, and both are located in the windiest area of the state.

No argument against Y and in favour of X.

B. The total population of County Y is substantially greater than that of County X.

In the example we have taken above, the population of Y is substantially greater than that of X

C. Some of the electricity generated by wind farms in County Y would be purchased by users outside the county.

Irrelevant. Doesn't give an argument against Y in favour of X. Same may happen if installed in county X. How electricity will be used is immaterial. We are focusing on where it is more feasible to set up the farm.

D. Wind farms require more land per unit of electricity generated than does any other type of electrical-generation facility.

We are not looking for arguments against wind based electricity generation.

E. Nearly all of County X’s population is concentrated in a small part of the county, while County Y’s population is spread evenly throughout the country.

We need vast stretches of land for a wind farm. X will probably have those since its population is concentrated so there will be sparsely populated areas too. In County Y, population is evenly distributed on land so we may not have vast areas of sparse population. It then makes better sense to set up the farm in X. This is correct.

Answer (E)
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adkikani, notice that the excellent explanation by VeritasPrepKarishma doesn't say anything about DEMAND. The author's argument has nothing to do with demand. The author believes that the wind farm should be built in Country Y simply because Country Y has a lower population density. And why does population density matter? Because wind farms "require vast expanses of open land."

Your analysis of choice (E) is perfect. Choice (C) has nothing to do with population density. We don't care who is purchasing the electricity. We only care about the amount of open land in each country. As explained by VeritasPrepKarishma, (C) is irrelevant.
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GMATNinja, VeritasPrepKarishma, adkikani
Guys just need a thought validation:

Based on answer choice B & Question stem we can conclude this:
X has less population(eg:1000) and higher density (concentrated in areas)
Y: has more population(eg:2000) and lower density. (Not as concentrated as people in X are)

Now cant we say based on the above facts that X has a better probability of providing more expanses of open land than Y because X has lesser population and higher density? Or could we reject B by saying that we don't know about the geographic placement of population chunks that E clearly states?

I see that E has a clear hit in piercing through the conclusion, But I am trying to find a better rejection explanation for B. I will appreciate any input.

Thanks
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Density of population is given by: No of people/Area of land
Higher density means more people or lesser area or both. It has nothing to do with how people are actually distributed across the available land area.

X has higher density than Y means either X has more number of people than Y (land area being the same) or X has lesser land area than Y (assuming same number of people) or both. If X has fewer people, it means its land area is even less.

Density of population does NOT tell us about how the population is spread across the region. Say 200 people per square mile could be evenly distributed across. Of course it is possible that the population is very unevenly distributed but option (B) doesn't give us any info about that. Option (E) clarifies the actual spread of the population across the region.
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Thanks VeritasPrepKarishma. Appreciate your input.
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Wind farms, which generate electricity using arrays of thousands of wind-powered turbines, require vast expanses of open land. County X and County Y have similar terrain, but the population density of County X is significantly higher than that of County Y. Therefore, a wind farm proposed for one of the two counties should be built in County Y rather than in County X.

Which of the following, if true, most seriously weakens the planner’s argument?

A. County X and County Y are adjacent to each other, and both are located in the windiest area of the state. - Out of Scope as this option choice does not speaks about Why setting up of Wind farms is favourable in Country X
B. The total population of County Y is substantially greater than that of County X.- Incorrect as despite of higher population of Country Y it is possible that land area required can be higher ending up with lower population density
C. Some of the electricity generated by wind farms in County Y would be purchased by users outside the country. - Out of Scope as it the end use of the electricity generated is not in question here. We are concerned with the feasibility of wind farms either in Country X or in Country Y
D. Wind farms require more land per unit of electricity generated than does any other type of electrical-generation facility.- [b]Irrelevant as we are not concerned with comparison of wind farms with other electrical generation facilities[/b]
E. Nearly all of County X’s population is concentrated in a small part of the county, while County Y’s population is spread evenly throughout the country - Correct as since X's population is concentrated in small parts so it shall require less open land. Therefore building of wind farms shall be feasible option in Country X

Please explain (B) why it is incorrect? NHasan19058

Posted from my mobile device
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Wind farms, which generate electricity using arrays of thousands of wind-powered turbines, require vast expanses of open land. County X and County Y have similar terrain, but the population density of County X is significantly higher than that of County Y. Therefore, a wind farm proposed for one of the two counties should be built in County Y rather than in County X.

Which of the following, if true, most seriously weakens the planner’s argument? Identify question type before reading. We see that it is a Weaken question. Want to make the conclusion less likely to be valid.

after reading the argument -- make sure to predict what could weaken. Maybe the population is all in one spot for X and Y actually has a lot more people, that are more spread out so less land available.

(A) County X and County Y are adjacent to each other, and both are located in the windiest area of the state.Eliminate. This does not weaken.

(B) The total population of County Y is substantially greater than that of County X. Okay -- but County Y may be a lot larger (even though "terrain" is similar. We can keep this around, but we will eliminate later on due to E.

(C) Some of the electricity generated by wind farms in County Y would be purchased by users outside the county. out of scope - eliminate.

(D) Wind farms require more land per unit of electricity generated than does any other type of electrical-generation facility. out of scope - eliminate.

(E) Nearly all of County X’s population is concentrated in a small part of the county, while County Y’s population is spread evenly throughout the country. this is exactly what we are looking for in our prediction for what could weaken. This is our answer.