In response to the increasing cost of producing energy through traditional means, such as combustion, many utility companies have begun investing in energy sources such as wind and solar power, hoping someday to rely on them completely and thus lower energy costs. The utility companies claim that these sources require an initial outlay of funds for construction and materials but then only a modest amount for maintenance. This makes them more economical than nonrenewable sources such as gas, oil, and coal, whose prices can fluctuate dramatically according to availability.
The claim of the utility companies presupposes which of the following?

A. The public will embrace the idea of wind and solar power.
B. No new deposits of gas, oil, and coal will be discovered in the near future
C. Weather patterns are consistent and predictable
D. The necessary technology for conversion to wind and solar power is not more
expensive than the technology needed for energy created through combustion.
E. Energy produced through combustion cannot be made more economical.

OA: C

I got this question in one of the manhattan's GMAT CATs. I marked the answer E because the reason for companies to shift to wind+gas is "increasing cost of producing energy through traditional means, such as combustion"...and option E assumes correctly that there is no cheaper/economical way to make combustion fuels. If we try the negation test then if there is any economical way then all this thing (wind+air) is not et all required and hence the argument shatters and weaken.

Instructors please reply.

Thanks!

GeeMate.

The question asks which answer choice the claim presupposes, so we are looking for an assumption that is NECESSARY. If we want to confirm an assumption as necessary, the conclusion needs to fail if we negate the assumption.

In E, more economical combustion energy does not totally ruin our conclusion that renewables are still more economical - just because combustion can be made more economical doesn't mean it will be enough to compete with the savings afforded by wind and solar. Your explanation assumes economy is an all-or-nothing switch ("if there is any economical way"), whereas in reality cost savings are amenable to numerical comparison (i.e. if we make something more economical something else can still outdo it in terms of economy).

On the other hand, we see that one of the big problems with nonrenewable sources is high prices due to unpredictability. If renewables are also unpredictable due to uncertainty about weather, presumably their prices can also fluctuate dramatically, thus negating the advantage that would otherwise have materialized.

_________________
Tim Sanders
Manhattan GMAT Instructor

I selected Option B in the test because if I negate it, new deposits of gas, oil and coal will be discovered in the near future and hence makes nonrenewable sources more dependable - doesn't this weaken the fact that new sources will be less risky compared to the nonrenewable sources?

I selected Option B in the test because if I negate it, new deposits of gas, oil and coal will be discovered in the near future and hence makes nonrenewable sources more dependable - doesn't this weaken the fact that new sources will be less risky compared to the nonrenewable sources?

If you negate it, that means that "some" new sources of gas, oil, and coal will be found, but it could be a very small amount that is not adequate to serve as energy. This negation is not as damaging to the conclusion as the negation of the correct answer.

_________________
Jamie Nelson
ManhattanGMAT Instructor

Even I selected answer as C. But I am trying top reason why D doesn't win the battle entirely.

Is it because it speaks of technology, hence out of scope or it doesn't speak of wind and water sources or both?

First, “out of scope” is NEVER a reason to get rid of an assumption question. If you are trying to find an assumption, then by definition it is something that is not mentioned in the passage, in other words something that is out of scope to a certain extent..
D is wrong because it doesn’t address the true claim of the companies, which has to do with the cost of maintenance. D address startup costs instead..

You may have struggled with the correct approach to this question because the original poster copied the text of the question incorrectly. As such, I am locking this thread so there is no more discussion of an incorrect version of the problem. There are other threads that address this question if you want to continue the discussion there..

_________________
Tim Sanders
Manhattan GMAT Instructor