Adding ethanol to the gasoline used in cars reduces exhaust emissions

Question

Which of me following best completes the passage below?

Adding ethanol to the gasoline used in cars reduces exhaust emissions while slightly increasing evaporation from gasoline tanks in cars and service stations. These evaporative emissions are a major component of the smog found in many large cities in the hot summer months but, except in hot weather, evaporative emissions pose less of a pollution problem than exhaust emissions do. Therefore, if air pollution were the only consideration, one could conclude that ______.

(A) ethanol should be added only to gasoline intended for use in large cities
(B) the benefits of using gasoline to which ethanol has been added are greater in hot weather than in cold weather
(C) the disadvantages of adding ethanol to gasoline are likely to be outweighed by the advantages, at least in cold weather
(D) it is not necessary to work at reducing exhaust emissions in large cities
(E) adding ethanol to the gasoline used in large cities will improve air quality in the cities in hot weather

GMATNinja · Accepted Answer

Let's take a second look at the passage: OK, so here's what we've got: Adding ethanol to gas reduces exhaust emissions. Adding ethanol to gas slightly increases evaporative emissions. Evaporative emissions are a major component of smog, which is found in many large cities in hot summer months. But evaporative emissions pose less of a pollution problem than exhaust emissions, except in hot weather. Therefore, if air pollution were the only consideration, one would conclude that ______________________________. The author tells us that evaporative emissions contribute to a kind of air pollution (smog), BUT this mainly happens in large cities and during hot summer months . When the weather is not hot, evaporative emissions pose less of a pollution problem than exhaust emissions. Our job is the fill in the blank, based on what the author has already said. Well, if air pollution is the only thing that we care about, then we know the author prefers evaporative emissions over exhaust emissions, except in hot weather (especially in hot weather within big cities). So just by reading the text, we can infer the author will prefer adding ethanol to gas except in hot weather (especially in hot weather within big cities). Addressing your concern about cold weather, recall that the author writes: "... except in hot weather , evaporative emissions pose less of a pollution problem than exhaust emissions." Here, the author is logically telling us: Evaporative emissions pose less of a pollution problem than exhaust emissions in all weather except hot weather . So we do know what the author thinks about the impact of ethanol during winter months (which it's safe to assume are cold, or at the very least, not hot). Now let's eliminate anything that's not consistent with the author's point of view: This is the opposite of what the author would like! We know that ethanol leads to more smog in large cities during hot summer months. The author would not recommend adding ethanol only to gasoline intended for use in these cities without some kind of targeted timing for when the ethanol is added. But this choice doesn't give us that kind of detail, so we eliminate (A). This is also the opposite of what the author has written so far. The author says that except in hot weather, evaporative emissions pose less of a pollution threat than exhaustive emissions. Eliminate (B). This looks good! When considering pollution, the author believes that the disadvantages of adding ethanol to gas match or outweigh the advantages in hot weather. Choice (C) states that the advantages of adding ethanol to gas (lower exhaust emissions) likely outweigh the disadvantages (slightly higher evaporative emissions), at least in cold weather (when there's less risk of the evaporative emissions contributing to smog). Let's keep (C) around. The author has spent the entire passage discussing how we can use ethanol to reduce exhaust emissions, in the context of a "pollution problem." Given that pollution is the only consideration for our answer, this would contradict, not complete, everything the author has already written. Eliminate (D). Like (A), this choice says the opposite of what the author has stated. Adding ethanol to gasoline in the cities in hot weather would contribute to smog, which is a form of air pollution. The end result would be lower air quality, not higher air quality. So eliminate (E). (C) is the best choice available. I hope this helped clear up the air around this question! I also hope my dad jokes don't exhaust anyone today!

(Wow, those jokes were some of my worst ever. Can I fire myself?)

ykaiim · Answer

I think it is E.

Reasoning:
Adding ethanol reduces the exhaust emission but slightly more evaporation, which is a major component of smog in large cities in hot summers. Then at the end the passge it concluded by saying "if air pollution were the  only  consideration".

seekmba · Answer

Adding ethanol ==> reduces exhaust emission and increases evaporative emission

evaporative emission ==> major component of smog found in large cities in hot summer months

evaporative emission ==> reduces air pollution compared to exhaust emission

If air pollution is only consideration....

(A) ethanol shoud be added only to gasoline for use in large cities ==> will not help in air pollution

(B) benefits of using gasoline to which ethanol has been added are greater in hot weather than in cold weather ==> not correct ==> because evaporative emission in ethanol is major component of smog in hot weather

(C) the disadvantages of adding ethanol to gasoline are likely to be outweighed by the advantages, at least in cold weather ==> not correct ==> the smog will actually be less in cold weather

(D) it is not necessary to work at reducing exhaust emissions in large cities ==>

(E) adding ethanol to the gasoline used in large cities will improve air quality in the cities in hot weather ==> correct ==> evaporative emission in ethanol is major component of smog in large cities in hot weather but it also poses less of air pollution which is in consideration here.

amp0201 · Answer

(A) ethanol should be added only to gasoline intended for use in large cities
  -- Irrelevant conclusion. Since this conclusion is focusing more on large cities rather than the advantages / disadvantages of using ethanol in gasoline. Hence A cannot be a correct answer choice.

(B) the benefits of using gasoline to which ethanol has been added are greater in hot weather than in cold weather
  -- Opposite to what the author wants to convey. Hence cannot be correct answer choice.

(C) the disadvantages of adding ethanol to gasoline are likely to be outweighed by the advantages, at least in cold weather
  -- The trap here I feel that many people might fall in is the phrase    likely to be outweighed by.    In other words we can state the answer choice as -   the advantages will outweigh the disadvantages of adding ethanol to gasoline, atleast in cold weather.  This is what we can conclude from the given premise. Hence C is correct answer choice.

(D) it is not necessary to work at reducing exhaust emissions in large cities
  -- Opposite to what the author wants to convey. Hence cannot be correct answer choice.

(E) adding ethanol to the gasoline used in large cities will improve air quality in the cities in hot weather
  -- Similar to D. Opposite to what the author wants to convey. Hence cannot be correct answer choice.

cssk · Answer

Can someone please tell me why B is wrong?

nechets · Answer

You have to read close the passage to understand the gist of this argument. I will try to highlight a few themes in the steem to help you out:

Adding ethanol to the gasoline used in cars reduces exhaust emissions while slightly increasing evaporation from gasoline tanks in cars and service stations. These evaporative emissions are a major component of the smog found in many large cities in the hot summer months but, except in hot weather, evaporative emissions pose less of a pollution problem than exhaust emissions do. Therefore, if air pollution were the only consideration, one could conclude that ______.

Premise 1: The combination of ethanol plus gasoline produces two opposite effects ---> Decrease "exhaust emissions", Increase "evaporation"

Premise 2: "Evaporation" polutes a lot in the  summer !

"except in hot weather" = except is a transition, it basically means "in the cold weather..."

Premise 3: "Evaporation" is not a big problem in the cold weather, but "exhaust emissios" are!"

Recalling the highlights, it becomes easy to rephrase a conclusion (our goal in this complete the argument question):  Gasoline plus ethanol increase "evaporation", but "evaporation" is not so bad in the winter. My conclusion is: better to add ethanol in the cold weather!

Answer B says:  (B) The benefits of using gasoline to which ethanol has been added are greater in hot weather than in cold weather -  Wait! This is a trap! It is exactly the opposite of the conclusion rephrased. I thought it was better to add ethanol in the cold weather...

Answer C says:   (C) the disadvantages of adding ethanol to gasoline are likely to be outweighed by the advantages, at least in cold weather  There you are! The cold weather and ethanol matches perfectly! "Evaporation" will polute less than "exhaust emisssion"

gmat1393 · Answer

Hi  GMATNinja

From the stimulus we dont know anything about cold weather.So how are we able to comment on what the advantages or disadvantages of adding ethanol to gasoline are in cold weather.

Can you please help in clarifying this? How C is the right answer here.

What am I missing here.

jeremqui · Answer

Does except in hot weather means cold weather?

Raman109 · Answer

Understanding the argument - 
Adding ethanol to the gasoline used in cars reduces exhaust emissions while slightly increasing evaporation from gasoline tanks in cars and service stations. - Fact 
These evaporative emissions are a major component of the smog found in many large cities in the hot summer months but, except in hot weather, evaporative emissions pose less of a pollution problem than exhaust emissions do. - Fact 
Therefore, if air pollution were the only consideration, one could conclude that ________.

Option Elimination -

(A) ethanol should be added only to gasoline intended for use in large cities - "only" is hyperbolic. 
(B) the benefits of using gasoline to which ethanol has been added are greater in hot weather than in cold weather - Opposite of what the argument states. 
(C) the disadvantages of adding ethanol to gasoline are likely to be outweighed by the advantages, at least in cold weather - ok
(D) it is not necessary to work at reducing exhaust emissions in large cities - "necessary" or "not necessary" is out of scope. 
(E) adding ethanol to the gasoline used in large cities will improve air quality in the cities in hot weather - Opposite of what the argument states.

VerbalBot · Answer

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Adding ethanol to the gasoline used in cars reduces exhaust emissions

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