Significant pollutant amongst automobile emissions is Nitrogen dioxide

CCs reduce NO2 emissions.
All new cars in Scotia since 2003 require CCs to be fitted in them.
NO2 emissions have reduced significantly in the country.
But not in New Durham though it has a high proportion of new cars.

Explain the paradox. There is a paradox, right? NO2 emissions have reduced in the country. New Durham has high proportion of new cars (cars with CCs) but still NO2 emissions have not reduced. Why?

There could be many reasons:
- Perhaps number of cars bought recently have increased tremendously so even with reduced NO2 emissions per car, overall NO2 emissions have stayed same in New Durham.
- Perhaps the way CCs work (the temperature they need etc) they are not suitable in New Durham.
etc

A. Many Scotians who own cars made before 2003 have had catalytic converters installed in their cars.

Info about Scotians is irrelevant. We need specific info about cars in New Durham.

B. Most car trips in Scotia's capital city are too short for the catalytic converter to reach its effective working temperature.

Correct. So this is reason why CCs are not effective in New Durham.

C. More of the cars in Scotia's capital city were made before 2003 than after 2003.

We are given that New Durham has a comparatively high proportion of new cars (supposedly compared to the rest of Scotia).
Even if most cars are old, it doesn't matter. If NO2 emission has reduced in the rest of Scotia even with lower proportion of new cars, it should certainly reduce in New Durham too with higher proportion of new cars.

D. The number of new cars sold per year in Scotia has declined slightly since 2003.

Info about Scotia is irrelevant. We need specific info about cars in New Durham.

E. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Scotia since 2003.

Other pollutants are irrelevant.

Answer (B)
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[quote="shreyashid"]Significant pollutant amongst automobile emissions is Nitrogen dioxide. Devices designed to reduce nitrogen dioxide emissions, known as Catalytic converters, have been required in all new cars in Scotia since 2003, and as a result, nitrogen dioxide emissions have been significantly reduced throughout most of the country. Yet although the proportion of new cars in Scotia's capital city, New Durham, has always been comparatively high, nitrogen dioxide emissions there have showed only an insignificant decline since 2003.

Which of the following, if true, most helps to explain the insignificant decline in nitrogen dioxide emissions in Scotia's capital city?

A. Many Scotians who own cars made before 2003 have had catalytic converters installed in their cars.
This does not explain the paradox.As,if converters were installed then N02 must decrease.

B. Most car trips in Scotia's capital city are too short for the catalytic converter to reach its effective working temperature.
Yes,we can keep this.Even if the cars have converters but they are not able to do their job.

C. More of the cars in Scotia's capital city were made before 2003 than after 2003.
Out of scope.

D. The number of new cars sold per year in Scotia has declined slightly since 2003.
Out of scope

E. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Scotia since 2003.
out of scope.we only want to talk about NO2[/quote]

+1 Kudo
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Let us identify the paradox first. Although all new cars in Scotia,since 2003, are required to have catalytic converters in the capital city of New Durham, the city with comparatively higher number of new cars, the decline in Nitrogen dioxide has been negligible. Any answer choice clarifying the reason behind this paradox is the answer. "B" clearly says that the trips made by the cars are so short that the converter does not even get a chance to function. Hence that is a possible explanation. If the converter does not work then it is obvious that the nitrogen dioxide will not decline even though the cars are new and are equipped with a converter. "C" goes against the fact because it is clearly stated that New Durham has comparatively higher number of new cars.
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It should be B.

For the simple reason that if the trips end before the Catalytic converters could start function, then it is equal to not installed.

In that case it is not effecctive and gives a reason why there is insignificant decrease in the level of No2.
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IMO - B.

Which of the following, if true, most helps to explain the insignificant decline in nitrogen dioxide emissions in Scotia's capital city?

A. Many Scotians who own cars made before 2003 have had catalytic converters installed in their cars.
This option is opposite to the question. If old car owners have installed catalytic converters, we should expect more decline not less.[color=#00a651]

B. Most car trips in Scotia's capital city are too short for the catalytic converter to reach its effective working temperature.
Correct answer. If catalytic converter doesn't work for shorter trips and most of the trips are short. We can explain the insignificant reduction.

C. More of the cars in Scotia's capital city were made before 2003 than after 2003.
This could be an answer but the author has asked about in proportion to the new car sold. Hence not so relevant.

D. The number of new cars sold per year in Scotia has declined slightly since 2003.
Very similar to option C explanation. Just talking about in proportional reduction.

E. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Scotia since 2003.
Author is talking about nitrogen dioxide reduction so irrelevant.

If we revise Answer A a little bit, it will present a possible explanation to resolve the paradox.
Many cars in New Durham already have installed converter before 2003, therefore, we can not observe a significant decline since 2003 when installing the converter became compulsory.
What is wrong here is it refers to Scotia as a whole => it can not explain the difference between Durham and other parts of Scotia.

GMATNinja VeritasKarishma why is C not a viable option here? If there are greater number of older cars, not having the converters we would expect the emissions to not reduce. Kindly help me understand the gap in my logic.
Thanks

Sidharth003
Watch out for the question stem. Question says that proportion of the new cars has always been high in the capital city.
Consider any year before 2003,
New Cars: Old cars = 70: 30
No Catalytic converters, so pollution was always high. For argument's sake, pollution was caused by 100 cars.

After 2003, let us assume some change in proportion. [Note: this change is worst case scenario, both positive and no change scenarios right away does not help in resolving the paradox]
New Cars:Old cars = 60:40. Now that catalytic converters in place, we should at least be seeing 60% reduction in pollution caused. Because, there is a new device fitted in cars, and they control the Nitrogen dioxide from those cars. But we are not seeing the same. So, option C does not help resolve the paradox.

CCs reduce NO2 emissions.
All new cars in Scotia since 2003 require CCs to be fitted in them.
NO2 emissions have reduced significantly in the country.
But not in New Durham though it has a high proportion of new cars.

Explain the paradox. There is a paradox, right? NO2 emissions have reduced in the country. New Durham has high proportion of new cars (cars with CCs) but still NO2 emissions have not reduced. Why?

There could be many reasons:
- Perhaps number of cars bought recently have increased tremendously so even with reduced NO2 emissions per car, overall NO2 emissions have stayed same in New Durham.
- Perhaps the way CCs work (the temperature they need etc) they are not suitable in New Durham.
etc

A. Many Scotians who own cars made before 2003 have had catalytic converters installed in their cars.

Info about Scotians is irrelevant. We need specific info about cars in New Durham.

B. Most car trips in Scotia's capital city are too short for the catalytic converter to reach its effective working temperature.

Correct. So this is reason why CCs are not effective in New Durham.

C. More of the cars in Scotia's capital city were made before 2003 than after 2003.

We are given that New Durham has a comparatively high proportion of new cars (supposedly compared to the rest of Scotia).
Even if most cars are old, it doesn't matter. If NO2 emission has reduced in the rest of Scotia even with lower proportion of new cars, it should certainly reduce in New Durham too with higher proportion of new cars.
Sidharth003

D. The number of new cars sold per year in Scotia has declined slightly since 2003.

Info about Scotia is irrelevant. We need specific info about cars in New Durham.

E. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Scotia since 2003.

Other pollutants are irrelevant.

Answer (B)
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I think this dubious question is a copy-and-paste job of this official GMAT Prep question. Not only does this question appear only on this site—curious for an apparent Paper Tests question that should have been floating around for years—but the overlap in phrasing and shuffled answer choices serve as caution signs. Why, for instance, is Catalytic capitalized in the middle of the second sentence? The other question, which I will quote below, places that word at the head of the second sentence, capitalizing it appropriately. Compare:




Although it is true that GMAC™ occasionally creates multiple versions of the same question or recycles a passage but pairs it with a different question, I have not come across any pair of clearly related questions such as those above, in which answer choice (A) became (C), (B) became (D), (C) became (E), (D) became (A), and (E) became (B): every answer choice was down-shifted by two slots and given a makeover.

I advocate removing the GMAC Paper Tests tag unless such a source can be verified.

- Andrew
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