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In 1986, the city of Los Diablos had 20 days on which air

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In 1986, the city of Los Diablos had 20 days on which air [#permalink] New post 21 Aug 2012, 10:44
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In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?
(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.
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Re: expert help needed [#permalink] New post 21 Aug 2012, 11:39
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siddharthasingh wrote:
In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?
(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.



1) Picture what's going on in this question through visualization in your head.

The # of days for "unhealthy" pollution levels rose from 20 days, to 31, 39, then dropped to 16 in the last year.

2) Something must explain why the numbers rose then fell. We know there was some control measures enacted in 1987 (the second year). But we then see an increase then a decrease 2 years later. Why?

(A) Helps explain - if they were not put into effect until end of 1988, we wouldn't see results until 1989 (the last year)

(B) Does not explain - the idea of a new gas spectrometer being invented is not linked to the counting of unhealthy days NOR is it linked to any increase then decrease in # of unhealthy days. Inventing an instrument has no effect on data - unless there's a specific link - the closest possible link is that all the data was bogus before and only the last year was accurate because a more accurate instrument was used and captured a far lower figure. But since the drop is so big, this possibility is extremely unlikely.

(C) Helps Explain - By revising the scale, what is considered harmful enough to count as an "unhealthy" day will drastically affect the numbers. What may have been 30 days under the old scale, could suddenly drop down to 16. So this could help explain (if implemented in the last year) why that last year figure is so low

(D) Helps Explain - 1988 levels were really high - might have been because the mayor accepted donations and he let industries pollute more that year

(E) Helps Explain - well if it takes 2 years in atmosphere to see the results, that's prob why we still had 2 bad years (tho mb doesn't explain the increase). Then in the last year it drops.

Hope that helps!
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Re: expert help needed [#permalink] New post 21 Aug 2012, 12:53
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gmatpill wrote:
siddharthasingh wrote:
In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?
(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.




1) Picture what's going on in this question through visualization in your head.

The # of days for "unhealthy" pollution levels rose from 20 days, to 31, 39, then dropped to 16 in the last year.

2) Something must explain why the numbers rose then fell. We know there was some control measures enacted in 1987 (the second year). But we then see an increase then a decrease 2 years later. Why?

(A) Helps explain - if they were not put into effect until end of 1988, we wouldn't see results until 1989 (the last year)

(B) Does not explain - the idea of a new gas spectrometer being invented is not linked to the counting of unhealthy days NOR is it linked to any increase then decrease in # of unhealthy days. Inventing an instrument has no effect on data - unless there's a specific link - the closest possible link is that all the data was bogus before and only the last year was accurate because a more accurate instrument was used and captured a far lower figure. But since the drop is so big, this possibility is extremely unlikely.

(C) Helps Explain - By revising the scale, what is considered harmful enough to count as an "unhealthy" day will drastically affect the numbers. What may have been 30 days under the old scale, could suddenly drop down to 16. So this could help explain (if implemented in the last year) why that last year figure is so low

(D) Helps Explain - 1988 levels were really high - might have been because the mayor accepted donations and he let industries pollute more that year

(E) Helps Explain - well if it takes 2 years in atmosphere to see the results, that's prob why we still had 2 bad years (tho mb doesn't explain the increase). Then in the last year it drops.

Hope that helps!

How did you know that these local industries, which were exempted by the mayor, cause pollution.
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Re: expert help needed [#permalink] New post 22 Aug 2012, 20:18
siddharthasingh wrote:
In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?
(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.


Here's my take

A - Once put into effect in Nov 1988, the measures can show effect in 1989. Therefore, this option helps explain.

C - Once again helps explain

E - Helps explain

Leaves us with B and D.

Both of which seem to not explain.

B - Invention does not necessarily mean adoption. A more accurate spectrometer was invented but that does not mean that the city actually used this. We don't know if it used this or not.

D - Similarly this option talks about mayor taking donations and exempting the industries in the following year from those measures. Why would industries be exempted from pollution controls if they did not pollute ?? (Beats logic). And the same year when the pollution went up? It seems to explain to me.

So B seems to be the answer.
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Re: expert help needed [#permalink] New post 22 Aug 2012, 23:38
mvikred wrote:
siddharthasingh wrote:
In 1986, the city of Los Diablos had 20 days on which air pollution reached unhealthful amounts and a smog alert was put into effect. In early 1987, new air pollution control measures were enacted, but the city had smog alerts on 31 days that year and on 39 days the following year. In 1989, however, the number of smog alerts in Los Diablos dropped to sixteen. The main air pollutants in Los Diablos are ozone and carbon monoxide, and since 1986 the levels of both have been monitored by gas spectrography.
Which of the following statements, assuming that each is true, would be LEAST helpful in explaining the air pollution levels in Los Diablos between 1986 and 1989?
(A) The 1987 air pollution control measures enacted in Los Diablos were put into effect in November of 1988.
(B) In December of 1988 a new and far more accurate gas spectrometer was invented.
(C) In February of 1989, the Pollution Control Board of Los Diablos revised the scale used to determine the amount of air pollution considered unhealthful.
(D) In 1988 the mayor of Los Diablos was found to have accepted large campaign donations from local industries and to have exempted those same industries from air pollution control measures.
(E) Excess ozone and carbon monoxide require a minimum of two years to break down naturally in the atmosphere above a given area.


Here's my take

A - Once put into effect in Nov 1988, the measures can show effect in 1989. Therefore, this option helps explain.

C - Once again helps explain

E - Helps explain

Leaves us with B and D.

Both of which seem to not explain.

B - Invention does not necessarily mean adoption. A more accurate spectrometer was invented but that does not mean that the city actually used this. We don't know if it used this or not.

D - Similarly this option talks about mayor taking donations and exempting the industries in the following year from those measures. Why would industries be exempted from pollution controls if they did not pollute ?? (Beats logic). And the same year when the pollution went up? It seems to explain to me.

So B seems to be the answer.


Just to add to above points for option D: It does not explain what happens post 1988. Was expemtion removed? There is no mention of this assumption. Also it does not state since when was exemption given. Was exemption applicable in 1986 and 1987?

So per me b/w b and D , D option has an edge.
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Re: expert help needed [#permalink] New post 23 Aug 2012, 00:16
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how come d has an edge. As mentioned earlier, adaption of a machine and machine inventing a machine are two very different things.
The key point is the reason everyone is eliminating D because they are assuming that these local industries were the ones that caused pollution.
I am not getting it.
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Re: expert help needed   [#permalink] 23 Aug 2012, 00:16
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