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# Photovoltaic power plants produce electricity from sunlight.

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Director
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Photovoltaic power plants produce electricity from sunlight. [#permalink]

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08 Dec 2006, 23:15
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Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, is one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.

The conclusion of the argument is properly drawn if which one of the following is assumed?
(A) The cost of producing electric power at traditional plants has increased over the past 20 years.
(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.
(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.
(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 20 times the cost of producing power at traditional plants.
(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.

Please give reasons for ur choices....

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08 Dec 2006, 23:52
A- Merely repeats what's already said in the passage.
B-Amount of power produced is irrelevant.
D- Inconclusive.
E- Stregthens the passage. But it is not an assumption.

Left with C. So C.

Last edited by ncp on 10 Dec 2006, 12:05, edited 1 time in total.

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Director
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09 Dec 2006, 05:04
D is not weakening the conclusion as the expense to maintain the photovoltail plant has become 1-10th now and traditional power plants have become costlier...Any views?

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09 Dec 2006, 06:21
only way that the conclusion can be drawn is if D is assumed....max. 20 times....if it were more than 20, conclusion is wrong.

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09 Dec 2006, 07:58
I go for D...C is very extreme...

If cost of producing elec thru traditional methods 20 yrs ago was 20 times more than the photovoltaic one...so if photovoltaic cost has decreased to 1/10 and traditional costs have gone up then D is the only assumption i can get to...

whts the OA?

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Director
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09 Dec 2006, 08:10
the cost of producing electric power at photovoltaic power plants is one-tenth of what it was 20 years ago so
photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants
But what if even after the production price decrease the cost of photovoltaic power still higher than increased cost of traditional power sources?
It is obvious that some info is missing)) Looking at the answer choices... D is the only one that stregthens the argument.
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09 Dec 2006, 09:40
Lets put some numbers for option D.

Assume that 10 years ago, photovoltaic plants costed 19 times the cost of a traditional plant(T).

So PP = 19T

Lets say, after the improvements

PP=19T/10=1.9T

In the same time TP=T*(1+x)

But we dont know how much it increased.

if x > 0.9, then it strengthens the passage.

if x < 0.9, then it weakens the passage.

So D is inconclusive. C is not ambiguous. This was my reasoning. So I went for C.

Why is this reasoning incorrect? Will be vey helpful if one of you can explain.

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10 Dec 2006, 12:06
This post has been inactive for a while.

Can someone else provide their perspective?

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Senior Manager
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10 Dec 2006, 19:38
I agree with C too... Prasad your reasoning is right.. I thought the same too.. None but C is the only option which helps..

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11 Dec 2006, 04:04
vineetgupta wrote:
Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, is one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.

The conclusion of the argument is properly drawn if which one of the following is assumed?
(A) The cost of producing electric power at traditional plants has increased over the past 20 years.
(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.
(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.
(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 20 times the cost of producing power at traditional plants.

(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.

Please give reasons for ur choices....

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Director
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11 Dec 2006, 04:52
The OA is D.

C can be ambiguous here since we dont know by how much the traditional and photovoltaic plants differed 10 years ago.

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11 Dec 2006, 06:52
vineetgupta wrote:
Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, is one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.

The conclusion of the argument is properly drawn if which one of the following is assumed?

CPN (CostPhotovoltaicNow)=0.1CPB (CostPhotovoltaicBefore)
CFN (CostFossilNow)>CFB (CostFossilBefore)
Then
CPN<CFN

To be able to draw a conclusion that compares CPN and CFN we need an assumption that relates CPB and CFB:
if CPB<10CFB
then CPN=0.1CPB<CFB<CFN

Quote:
(A) The cost of producing electric power at traditional plants has increased over the past 20 years.

We already know that CFN is more than CFB. It doesn't matter if CF has been increasing over 20 years.
Quote:
(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.

We need (unit) cost figures. If we know quantity without how much total cost each type of plants have, we can't get to the cost comparison.
Quote:
(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.

Irrelevant.
Quote:
(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 20 times the cost of producing power at traditional plants.

CPB<20CFB
It's close, but still a little different from the real assumption that is needed. It might or might not render the conclusion correct.
Quote:
(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.

Not strong enough for saying CP today is smaller than CF today. If CP before is a million times more than CF before, even if it has been decreasing and will decrease further, it might not be cheaper today. What's going to happen in the future really is irrelevant to the conclusion as of today.

D is not good enough, but all the others are irrelevant. I would say this question is not designed properly. If the number in D is changed to 10, or if it is specified in the stem that the cost of fossil plant has doubled today, then D would be a perfect choice.
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11 Dec 2006, 12:25
Exactly my thoughts HongHu.

I chose C because I had to choose one.

I think the question is flawed.

See below for a consolidated post of all my earlier postings.

A- Merely repeats what's already said in the passage.
B-Amount of power produced is irrelevant.

D- Inconclusive.
Lets put some numbers for option D.

Assume that 10 years ago, photovoltaic plants costed 19 times the cost of a traditional plant(T).

So PP = 19T

Lets say, after the improvements

PP=19T/10=1.9T

In the same time TP=T*(1+x)

But we dont know how much it increased.

if x > 0.9, then it strengthens the passage.

if x < 0.9, then it weakens the passage.

So D is inconclusive.

E- Stregthens the passage. But it is not an assumption.

Left with C. So C.

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11 Dec 2006, 12:25
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