Critical Reasoning

Nitrogen dioxide is a pollutant emitted by automobiles. Catalytic converters, devices designed to reduce nitrogen dioxide emissions, have been required in all new cars in Donia since 1993 and as a result, nitrogen dioxide emissions have been significantly reduced throughout most of the country. Yet although the proportion of new cars in Donia's capital city has always been comparatively high, nitrogen dioxide emissions there have showed only an insignificant decline since 1993.

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

A. More of the cars in Donia's capital city were made before 1993 than after 1993
B. The number of new cars sold per year in Donia has declined slightly since 1993.
C. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Donia since 1993.
D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars
E. Most car trips in Donia's capital city are too short for the catalytic converter to reach its effective working temperature.

Why A is Out???
Destroyer pls come and help to solve this!! I need to know why A is out and why E is right?

tracyyahoo wrote:Nitrogen dioxide is a pollutant emitted by automobiles. Catalytic converters, devices designed to reduce nitrogen dioxide emissions, have been required in all new cars in Donia since 1993 and as a result, nitrogen dioxide emissions have been significantly reduced throughout most of the country. Yet although the proportion of new cars in Donia's capital city has always been comparatively high, nitrogen dioxide emissions there have showed only an insignificant decline since 1993.

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

A. More of the cars in Donia's capital city were made before 1993 than after 1993 --
B. The number of new cars sold per year in Donia has declined slightly since 1993.
C. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Donia since 1993.
D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars
E. Most car trips in Donia's capital city are too short for the catalytic converter to reach its effective working temperature.

Why A is Out???
Destroyer pls come and help to solve this!! I need to know why A is out and why E is right?

Hi-- I've highlighted the reason in RED to Eliminate option A. The scenario described in A that says -- cars made before 1993> cars made after 1993 can be discarded using this information

option E is correct because it helps to resolve the paradox. Option E clearly states the reason for the non-functioning of the 'Catalytic Converter' -- if they do not reach the minimum required temperature than obviously they will not be effecient in controlling the emission.

Hope this helps.

tracyyahoo wrote:Nitrogen dioxide is a pollutant emitted by automobiles. Catalytic converters, devices designed to reduce nitrogen dioxide emissions, have been required in all new cars in Donia since 1993 and as a result, nitrogen dioxide emissions have been significantly reduced throughout most of the country. Yet although the proportion of new cars in Donia's capital city has always been comparatively high, nitrogen dioxide emissions there have showed only an insignificant decline since 1993.

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

A. More of the cars in Donia's capital city were made before 1993 than after 1993
B. The number of new cars sold per year in Donia has declined slightly since 1993.
C. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Donia since 1993.
D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars
E. Most car trips in Donia's capital city are too short for the catalytic converter to reach its effective working temperature.

Why A is Out???
Destroyer pls come and help to solve this!! I need to know why A is out and why E is right?

the question is why the emissions have not reduced in the capital, asthey have in the rest of the country. Why have the emissions reduced in other places? over time, old cars come off the road, to be replaced by new cars, which do not emit NO because of the catalytic converters. So something must be interfering with this process in the capital.

The most important part of the analysis above is that the reductions is a PROCESS. the fact that the capital has more old cars than new cars does not explain why the process of replacing old with new over time does not achieve its natural result. All A does is give us statistic frozen in time: More than 50% are old.

E gives you a reason why the process of replacing old cars with new ones does not achieve the the required result of reduced emissions: the new cars don't travel long enough for the catalytic converter to have an effect, so replacing old with new does not bring about lower emissions - without the converters, the new cars emit the same NO as the old ones.

Neither of you help me to understand.

What you explain is that another way of solving this problem. But I want to know what clearly kills (A)? What you explain is not very persuasive to me.

Geva@MasterGMAT wrote:

tracyyahoo wrote:Nitrogen dioxide is a pollutant emitted by automobiles. Catalytic converters, devices designed to reduce nitrogen dioxide emissions, have been required in all new cars in Donia since 1993 and as a result, nitrogen dioxide emissions have been significantly reduced throughout most of the country. Yet although the proportion of new cars in Donia's capital city has always been comparatively high, nitrogen dioxide emissions there have showed only an insignificant decline since 1993.

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

A. More of the cars in Donia's capital city were made before 1993 than after 1993
B. The number of new cars sold per year in Donia has declined slightly since 1993.
C. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Donia since 1993.
D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars
E. Most car trips in Donia's capital city are too short for the catalytic converter to reach its effective working temperature.

Why A is Out???
Destroyer pls come and help to solve this!! I need to know why A is out and why E is right?

the question is why the emissions have not reduced in the capital, asthey have in the rest of the country. Why have the emissions reduced in other places? over time, old cars come off the road, to be replaced by new cars, which do not emit NO because of the catalytic converters. So something must be interfering with this process in the capital.

The most important part of the analysis above is that the reductions is a PROCESS. the fact that the capital has more old cars than new cars does not explain why the process of replacing old with new over time does not achieve its natural result. All A does is give us statistic frozen in time: More than 50% are old.

E gives you a reason why the process of replacing old cars with new ones does not achieve the the required result of reduced emissions: the new cars don't travel long enough for the catalytic converter to have an effect, so replacing old with new does not bring about lower emissions - without the converters, the new cars emit the same NO as the old ones.

new cars after 1993: less emissions (m just talking about nitrogen dioxide)
donia: less emissions
donia capital: although new cars proportionally high, insignificant decline in emission.
paradox question:
a) more cars are made before <1993. but it has been mentioned that proportion of new cars in donia capital has always been comparatively high. thus in Donia's other parts, proportion of new cars is less and even then emissions have reduced. thus in donia's capital, with relatively high proportion, emissions should have reduced (thus this doesn't explain paradox)

e) as converts do not reach effective working temp, they can't reduce emissions. thus insignificant decline

@ tracyyahoo: I hope you saw the part I highlighted in RED. The information given in A is exactly the opposite of the information given in the question. Hence, you can eliminate this choice straightway.

Cannot explain much. If you are still not able to understand it even now then I think you can just
Move on. There are thousands of other questions to solve.

Yeah, I think you are right, I need to move on, it just one thing

saketk wrote:@ tracyyahoo: I hope you saw the part I highlighted in RED. The information given in A is exactly the opposite of the information given in the question. Hence, you can eliminate this choice straightway.

Cannot explain much. If you are still not able to understand it even now then I think you can just
Move on. There are thousands of other questions to solve.

option A contradicts the premises ( Marked in red in one of the above post)
hence out

I am agree with why A is wrong and why E is correct, but can somebody explain whats wrong with D?

If even older cars had same device installed, so even those cars were emitting less nitrogen dioxide. So this fact give us clear reason why emission level didn't fall significantly as it was already lower.

@Calvin123

D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars

D does not say anything about Donia's Capital city. It just makes general statement about residents.
And this does not price less decline in capital city in anyway

dev.gavande wrote:@Calvin123

D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars

D does not say anything about Donia's Capital city. It just makes general statement about residents.
And this does not price less decline in capital city in anyway

True. Coupled with the fact that we don't actually know when the converters were installed (before 1993 or after 1993) - just that the cars were made before 1993.
If the converters were installed Before 1993, then Calvin is right, as that might explain why we didn't see a dramatic reduction after 1993. But if the converters were installed AFTER 1993, then D actually increases the paradox without resolving it - so many converters installed in new and old cars, and STILL no reduction in Nitrogen? Why, God, WHY?

Since D doesn't state the time of installing the converters, it might swing both ways, which already makes it a suspect answer. Besides, it makes more sense that owners of old cars would install the converters AFTER the laws mandating their use have passed in 1993, and not before.