GMATPrep CR question

[bakshi.puneet]

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.

I was stuck between A and E. Chose E, which happens to be the correct answer.

Can somebody (if possible Ron/Stacey) help me differentiating between A and E?
Is my reasoning below to through out A correct ? If so, is the same reasoning not true with E as well ?

A.
One of the premise says,
"proportion of new cars in Donia’s capital city has always been comparitively high". which means,
(%age new cars) in capital > (%age new cars) in other cities
Option A says that in capital, number of old cars is greater than no of new cars, which could very well be true. But, it is still possible that people in Donia's capital use old cars with additionally installed catalytic converter. We don’t know. Hence OUT.

E.
With almost similar reasoning as above, is "effective working temperature" not out of scope here? This may or may not be the contributing factor.

[RonPurewal]

A.
...Option A says that in capital, number of old cars is greater than no of new cars,

no.

if the "proportion of new cars has always been comparatively high", that means that there are MORE new cars, not less, in the capital city than in other regions.

also, "comparatively high" has nothing to do with whether there are more new cars vs. more old cars. (that would just be "high", not "comparatively high".
when you say "comparatively high", you're talking about this rate relative to other such rates -- i.e., relative to rates in other cities in the country of donia.

also, that's the only comparison that's really meaningful here, since we're trying to account for why the emissions in the capital city haven't gone down, while those in outlying cities have.

E.
With almost similar reasoning as above, is "effective working temperature" not out of scope here? This may or may not be the contributing factor.

you're using the wrong king of reasoning. this is not a "find the assumption" question.

ON "STRENGTHEN", "WEAKEN", AND, ESPECIALLY, "EXPLAIN THE DISCREPANCY" QUESTIONS, ALMOST EVERY CORRECT ANSWER WILL VENTURE OUTSIDE THE ORIGINAL SCOPE IN SOME WAY.
for the last of these - a category that includes the question examined in this thread - you actually can't answer the question without going outside the scope; it's a logical impossibility. after all, the passage contains a "discrepancy" that is NOT EXPLAINED BY WHAT IS IN THE PASSAGE; this is the whole point of the question! so you MUST introduce something from outside the original scope.

notice the question prompt - perhaps you've never taken an overly careful look at it:
Which of the following, if true,

if the prompt contains the words "IF TRUE...", then you do not have to stay within the scope of the passage.

[sandeep.19+man]

The extract says "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."

Proportion of new cars in
Other cities = 2%
Donia's capital city = 3%

Therefore couldnt (A) be correct as well? Am I missing something?

(A) More of the cars in Donia's capital city were made before 1993 than after 1993

[RonPurewal]

The extract says "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."

Proportion of new cars in
Other cities = 2%
Donia's capital city = 3%

Therefore couldnt (A) be correct as well? Am I missing something?

(A) More of the cars in Donia's capital city were made before 1993 than after 1993

you are not paying enough attention to what this problem is actually asking you to do.

your question -- "couldn't (a) be correct?" -- is irrelevant to the matter at hand. in fact, ALL of the choices could be correct; moreover, when you consider each choice, you actually assume that it is correct (this is the essence of the words "if true" in the problem statement).

instead, you are looking for which of the choices EXPLAINS THE UNEXPECTED RESULT that is observed in the passage -- the fact that donia has seen a smaller reduction in emissions than have the other cities, even though it has a "comparatively high" proportion of new cars.
this choice does not help to explain that result -- even with your percentages (3% and 2%), we would still expect to see a 3:2 ratio of emissions reduction in donia vs. the outlying cities.

the only answer choice that explains why there is LESS of an emissions reduction in the capital city, even though there are MORE new cars there, is (e).

[rajanbond]

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
This is completely opposite of what is stated and weakens the argument
B. The number of new cars sold per year in Donia has declined slightly since 1993.
Irrelevant. We are talking about the capital city
C. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Donia since 1993.
irrelevant
D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars
This would mean that pollution should be down and not up

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

How do we explain that even though the capital city has more new cars relatively, the pollution levels have not gone down for Nitrogen dioxide.
If somehow, the catalytic converter was not working as expected in the new cars, then even new cars will emit nitrogen dioxide.

This is stated explicitly in E

[mschwrtz]

That looks like a very good account of the merits of the answers.

[aagar2003]

can somebody pls elaborate on the usage of 'yet' here? I thought 'yet' should be in contrast to sentence/argument presented earlier, but that is not the case. Could the sentence that contains 'yet' be written w/o 'Yet' and start from 'Although'?

Because of 'yet', I had hard time understanding what comparatively high is used in comparison to?

[RonPurewal]

Could the sentence that contains 'yet' be written w/o 'Yet' and start from 'Although'?

no.
"yet" connects that sentence to the rest of the paragraph, while "although" relates the two clauses within that sentence. you need both.
you could replace "yet" with, say, "however", but you can't just take it out.

Because of 'yet', I had hard time understanding what comparatively high is used in comparison to?

"comparatively high" means higher than the corresponding statistic in most other areas.
this is not the kind of thing for which you need to specify the counterpart exactly; it's just assumed to be "others".
e.g.
Blox University has a comparatively high dropout rate --> this sentence is ok by itself; it's understood that we mean "relative to other universities to which B.U. is comparable".

I thought 'yet' should be in contrast to sentence/argument presented earlier, but that is not the case.

from these comments it's clear that you aren't understanding the argument correctly. there is most definitely a contrast; in fact, the contrast is the whole point of the problem.
the problem asks you to "explain the insignificant decline" precisely BECAUSE that small decline is *not* what would be expected from the previously presented information. if there were no such contrast, then there would be no problem to answer here.

[manhhiep2509]

The extract says "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."

Proportion of new cars in
Other cities = 2%
Donia's capital city = 3%

Therefore couldnt (A) be correct as well? Am I missing something?

(A) More of the cars in Donia's capital city were made before 1993 than after 1993

you are not paying enough attention to what this problem is actually asking you to do.

your question -- "couldn't (a) be correct?" -- is irrelevant to the matter at hand. in fact, ALL of the choices could be correct; moreover, when you consider each choice, you actually assume that it is correct (this is the essence of the words "if true" in the problem statement).

instead, you are looking for which of the choices EXPLAINS THE UNEXPECTED RESULT that is observed in the passage -- the fact that donia has seen a smaller reduction in emissions than have the other cities, even though it has a "comparatively high" proportion of new cars.
this choice does not help to explain that result -- even with your percentages (3% and 2%), we would still expect to see a 3:2 ratio of emissions reduction in donia vs. the outlying cities.

the only answer choice that explains why there is LESS of an emissions reduction in the capital city, even though there are MORE new cars there, is (e).

Hi Ron.

You said "donia has seen a smaller reduction in emissions than have the other cities", but I have not yet seen a comparison between the emission of the capital and that of other cities.

I only see that the author is comparing the emission levels of the capital before 1993 and after 1993.

So, I eliminate choice A because whether it can explain the paradox depends on assumption, meanwhile choice E clearly indicates the cause.

What did I miss here?

[RonPurewal]

The passage states that "the proportion of new cars in Donia's capital city has always been comparatively high".
"Comparatively high" means we're comparing the proportion of new cars in the capital with the same proprtion ... somewhere else.

The only sensible interpretation is that we're comparing the % in the capital with the % in other cities.

[gbyhats]

Hi Dear Manhattan Instructors ;)

your question -- "couldn't (a) be correct?" -- is irrelevant to the matter at hand. in fact, ALL of the choices could be correct; moreover, when you consider each choice, you actually assume that it is correct (this is the essence of the words "if true" in the problem statement).

Acknowledging Ron's word, I still can't stop resist asking why (D) is wrong... I'm sorry... My brain stop functioning for this question...

--

My reasoning:

Because citizens in Donia have been using catalytic converters long before 1993, so there will be no significant drop in nitrogen dioxide emission since 1993

An analogy:

I have learned the basic English vocabularies before I took Ron's class. So giving a mandatory assignment that ask me to learn basic English vocabularies won't make me much better in understanding Ron's class.

[RonPurewal]

you're misinterpreting choice D--actually, in three different (and all major) ways.

go back and read the words in choice D again--this time slowly, carefully, and SLOWLY. (yes, two "slowly"s... because it's that important.)

(see below)

[RonPurewal]

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

versus yours:

Because citizens in Donia have been using catalytic converters long before 1993, ...

blue issue:
you're taking "many donians" to mean donians in general.
nope.
in fact, "many xxxx" usually implies "NOT a majority".

purple issue:
this choice just says that these people own pre-1993-model cars. there's no indication that the catalytic converters were installed before 1993.
in fact, the choice states that these people "have had catalytic converters installed in their cars"--implying that they bought the car at some point, but didn't have the CC installed until later.

[RonPurewal]

...and the third issue, which should allow you to eliminate choice D instantly:
choice D has nothing to do with the capital city!

the whole point of the entire passage is that the capital city is a weird exception to an observation that's generally true throughout the rest of the country.

if we want to explain why the capital city is a weird exception, then, clearly, the correct answer must actually say something specifically about the capital city.

(common-sense analogy: All five of these dishes look good, but you shouldn't eat the broccoli. --> if you ask me to explain this, then, clearly, i need to tell you something about the broccoli!)

this humble observation alone is enough to narrow the choices to just A and E.

[gbyhats]

Hi Dear Ron ;)

you're misinterpreting choice D--actually, in three different (and all major) ways.

go back and read the words in choice D again--this time slowly, carefully, and SLOWLY. (yes, two "slowly"s... because it's that important.)

Thank you very much for your three consecutive replies!

Now I got it!

I'm ignorant enough to overlook three mistakes embedded in choice (D).

Which reminds me of:

"Two things are infinite: the universe and human stupidity."
--Albert Einstein