BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Ethanol

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 510
Joined: Thu Aug 07, 2014 2:24 am
Thanked: 3 times
Followed by:5 members

Ethanol

by j_shreyans » Sat Aug 22, 2015 6:03 pm
Studies have shown that an automobile that runs on a blend of 85% ethanol/15% gasoline gets better mileage than an otherwise similar car equipped with a gasoline engine. Many American legislators have concluded that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil.

Which of the following, if true, casts the most doubt upon the validity of the legislators' conclusion?

A)It takes 1.5 gallons of oil to produce 1 gallon of ethanol.

B)Electric cars are cheaper to operate than cars running on the ethanol fuel mix.

C)It costs thousands of dollars to retrofit an automobile to run on the ethanol fuel mix.

D)The ethanol/gasoline blend emits more pollution that regular gasoline.

E)The ethanol/gasoline blend has not been widely adopted in Europe.


OA A

Experts please explain.

Thanks
Top
Source: — Critical Reasoning |
User avatar
Legendary Member
Posts: 2135
Joined: Mon Feb 03, 2014 9:26 am
Location: https://martymurraycoaching.com/
Thanked: 955 times
Followed by:140 members
GMAT Score:800

by MartyMurray » Sat Aug 22, 2015 9:41 pm
The conclusion of the argument is that by increasing tax incentives and thus getting people using ethanol, we will use less oil and thus decrease dependence on foreign oil. This is based on the fact that cars get better mileage when they use a blend of ethanol and gasoline than they do when they use just gasoline.

This argument is a little funny actually, because I am not sure what the real point is. Is the point that the mileage is better when ethanol is used? or is it that ethanol is a decent substitute for part of the gasoline and so less gasoline is used and therefore less oil, which is used to produce gasoline, is used?

Anyway, even with that possible ambiguity there's a way to get the right answer.

A)It takes 1.5 gallons of oil to produce 1 gallon of ethanol.

This immediately jumps out as the right answer. Supposedly by using ethanol we can use less oil, but look, it takes a more than a gallon of oil to produce a gallon of ethanol. So even if ethanol works well in cars, and if we therefore were to use ethanol for fuel, the truth is that effectively we would still be using a lot of oil, to produce the ethanol.

So I am guessing this is the answer, but I am still going to check the rest. There could be an even better one, especially as this one has a slight vulnerability to it in that maybe cars get such better mileage with ethanol that even though it takes oil to make ethanol one can still reduce use of oil by using ethanol.

B)Electric cars are cheaper to operate than cars running on the ethanol fuel mix.

This is a typical trap answer used in CR questions involving plans. These trap answers often indicate that the plan is not the best plan available. The thing is the question is about whether the plan is the best plan. The question is about why the plan itself wouldn't work. A plan could work fine without being the best plan, and so this answer choice is irrelevant.

C)It costs thousands of dollars to retrofit an automobile to run on the ethanol fuel mix.

This is another typical trap answer, one involving a topic shift. The conclusion we are seeking to weaken is about use of foreign oil. This answer choice is about cost to retrofit cars. There could be a high cost to retrofitting cars and the plan would still reduce use of oil. So this choice does not affect the conclusion.

D)The ethanol/gasoline blend emits more pollution that regular gasoline.

Here we go again. So the plan might not be a good plan, because in achieving its goal the plan delivers negative consequences, but that does not mean that the plan would not succeed in achieving its goal of reducing use of oil.

E)The ethanol/gasoline blend has not been widely adopted in Europe.

Maybe in the real world this could be a red flag that there is some issue with the plan. If others have not adopted a similar plan, maybe there is some reason they haven't. At the same time, in choice A there is an actual reason why the plan likely won't work, while this choice merely gives us a reason to wonder if there is a reason.

So even with the ambiguity of the prompt and the lack of a specific number to tell us what "get's better mileage" means, the answer choice that casts the "most doubt" on the validity of the legislators' conclusion that the plan will work is A.
Last edited by MartyMurray on Sun Aug 23, 2015 9:27 am, edited 1 time in total.
Marty Murray
Perfect Scoring Tutor With Over a Decade of Experience
MartyMurrayCoaching.com
Contact me at [email protected] for a free consultation.
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Sun Aug 23, 2015 8:42 am
j_shreyans wrote:Studies have shown that an automobile that runs on a blend of 85% ethanol/15% gasoline gets better mileage than an otherwise similar car equipped with a gasoline engine. Many American legislators have concluded that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil.

Which of the following, if true, casts the most doubt upon the validity of the legislators' conclusion?

A)It takes 1.5 gallons of oil to produce 1 gallon of ethanol.

B)Electric cars are cheaper to operate than cars running on the ethanol fuel mix.

C)It costs thousands of dollars to retrofit an automobile to run on the ethanol fuel mix.

D)The ethanol/gasoline blend emits more pollution that regular gasoline.

E)The ethanol/gasoline blend has not been widely adopted in Europe.
The key with weaken the argument questions to constantly remind ourselves of the conclusion that we are trying to weaken.

Here, the conclusion is: an increase in tax incentives for ethanol production would lessen our dependence on foreign oil.
So, each time we read an answer choice, we should ask ourselves, "Does this information weaken the conclusion that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil?

If you wish, you can shorten the conclusion to save time. However, be sure to keep asking whether each answer choice weakens the conclusion that....

A)It takes 1.5 gallons of oil to produce 1 gallon of ethanol.
"Does this information weaken the conclusion that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil?
Yes! We end up using MORE oil this way.

B)Electric cars are cheaper to operate than cars running on the ethanol fuel mix.
"Does this information weaken the conclusion that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil?
This information has NOTHING to do with the conclusion that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil
ELIMINATE B

C)It costs thousands of dollars to retrofit an automobile to run on the ethanol fuel mix.
"Does this information weaken the conclusion that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil?
This information has NOTHING to do with the conclusion that an increase in tax incentives for ethanol production would lessen our dependence on foreign oil
ELIMINATE C

And so on.

Answer: A

For more on this, watch our free video on solving Weaken the Argument questions: https://www.gmatprepnow.com/module/gmat- ... ng?id=1136

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Post new topic Post Reply
• Page 1 of 1