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by jainrahul1985 » Wed Sep 07, 2011 12:49 am
The U.S. census is not perfect: thousands of Americans probably go uncounted. However, the basic statistical portrait of the nation painted by the census is accurate. Certainly some of the poor go uncounted, particularly the homeless; but some of the rich go uncounted as well, because they are often abroad or traveling between one residence and another.
Which of the following is an assumption on which the argument above depends?



(A) Both the rich and the poor have personal and economic reasons to avoid being counted by the census.
(B) All Americans may reasonably be classified as either poor or rich.
(C) The percentage of poor Americans uncounted by the census is close to the percentage of rich Americans uncounted.
(D) The number of homeless Americans is approximately equal to the number of rich Americans.
(E) The primary purpose of the census is to analyze the economic status of the American population

OA C . Experts please explain in detail . I found this question very tricky .
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by sunnyjohn » Wed Sep 07, 2011 1:07 am
It's a good question.

Assumption + Number/Percentage

F1: Some of poor are not counted.
F2: Some of rich are not counted.
Conclusion: Census is not perfect but it does give accurate info about basic statistics about nation.

Since quite a few people are not counted so its obvious census is not perfect, then why did Author said that census provide accurate national statistics.

Key to this answer is "ASSUMPTION." Overall I will look for an answer which will provide a link which can explain that even though we miss few people we will still provide accurate statistics.

(A) Both the rich and the poor have personal and economic reasons to avoid being counted by the census.
It talks about reason people have to avoid being counted. ( OUT OF SCOPE )

(B) All Americans may reasonably be classified as either poor or rich.
Too big in scope, we don't care how Americans are classified.

(C) The percentage of poor Americans uncounted by the census is close to the percentage of rich Americans uncounted.
It means out if 10% of poor people were not counted, then around 10% of rich people were also not counted.
Overall all stats will be deducted using 90% of poor people and 90% of rich people. ( This connects our two missing piece)

(D) The number of homeless Americans is approximately equal to the number of rich Americans.
Out of 1000 poor people, 100 were not counted Vs 100,00 Rich people, 100 were not counted. 90% of poor people Vs 99% of Rich people.This means Statistics will surely be inclined toward Rich people, hence it wont be accurate. So this option does not necessary to be assumption.


(E) The primary purpose of the census is to analyze the economic status of the American population
why in the world we care what was the purpose of census.
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by Geva@EconomistGMAT » Wed Sep 07, 2011 1:09 am
jainrahul1985 wrote:The U.S. census is not perfect: thousands of Americans probably go uncounted. However, the basic statistical portrait of the nation painted by the census is accurate. Certainly some of the poor go uncounted, particularly the homeless; but some of the rich go uncounted as well, because they are often abroad or traveling between one residence and another.
Which of the following is an assumption on which the argument above depends?



(A) Both the rich and the poor have personal and economic reasons to avoid being counted by the census.
(B) All Americans may reasonably be classified as either poor or rich.
(C) The percentage of poor Americans uncounted by the census is close to the percentage of rich Americans uncounted.
(D) The number of homeless Americans is approximately equal to the number of rich Americans.
(E) The primary purpose of the census is to analyze the economic status of the American population

OA C . Experts please explain in detail . I found this question very tricky .
For many assumption questions, it pays to use "weakening" type thinking to expose the assumption.

the argument claims that the census paints an accurate picture because it misses some poor, but also misses some rich as well. Think - why would this be wrong? How could the premises be right (miss some poor, miss some rich), but the conclusion be wrong (paint a distorted picture of the population - count a higher percentage of rich or poor in the population than there actually are)?

What if...the "some" were not the same for both parts of the population? The argument doesn't tell us what "some" is - if we miss 5% of the poor, but 40% of the rich, the picture painted by the censues will be skewed.

Thus, in order to reach the conclusion that the census paints an accurate picture, the author must assume that the percentage missed in both cases is about the same, so the resulting statistical description, while a flawed picture of reality, is at least flawed equally for rich and poor alike.
Once you have that, C is the only obvious choice.

Which answer choice did you struggle with, and why?
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by badpoem » Wed Sep 07, 2011 1:16 am
Let us take a sample data. Suppose, there are 100 people in the US, out of which 65 are rich and 35 are poor.

Now, according to the stem --> ...thousands of Americans probably go uncounted. However, the basic statistical portrait of the nation painted by the census is accurate...

So we have two scenarios - 1) ideal and 2) not ideal. Say in the 'not ideal' scenario, 50 people are not counted. Out of the 50 counted, we have 33 rich and 17 poor. This is keeping in line with the above premise.

Then,

Total Rich Poor
Ideal Scenario (everyone counted) 100 65 35
Not ideal (not everyone counted) 50 33 17

percentage of poor not counted = (35-17)/35 * 100 ~~ 50%
percentage of rich not counted = (65-33)/65 * 100 ~~ 50%

So C--> The percentage of poor Americans uncounted by the census is close to the percentage of rich Americans uncounted. is TRUE.

But,

1) I arrived at this conclusion after doing this maths and I do not think this shall be the best idea when I will encounter a problem such as this on the real GMAT. Experts, can you show a better way?

2) Also, I was initially vacillating between B and C. Is B not a relevant assumption (since we are more concerned about the details of the census) ?
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by Geva@EconomistGMAT » Wed Sep 07, 2011 3:21 am
badpoem wrote:Let us take a sample data. Suppose, there are 100 people in the US, out of which 65 are rich and 35 are poor.

Now, according to the stem --> ...thousands of Americans probably go uncounted. However, the basic statistical portrait of the nation painted by the census is accurate...

So we have two scenarios - 1) ideal and 2) not ideal. Say in the 'not ideal' scenario, 50 people are not counted. Out of the 50 counted, we have 33 rich and 17 poor. This is keeping in line with the above premise.

Then,

Total Rich Poor
Ideal Scenario (everyone counted) 100 65 35
Not ideal (not everyone counted) 50 33 17

percentage of poor not counted = (35-17)/35 * 100 ~~ 50%
percentage of rich not counted = (65-33)/65 * 100 ~~ 50%

So C--> The percentage of poor Americans uncounted by the census is close to the percentage of rich Americans uncounted. is TRUE.

But,

1) I arrived at this conclusion after doing this maths and I do not think this shall be the best idea when I will encounter a problem such as this on the real GMAT. Experts, can you show a better way?

2) Also, I was initially vacillating between B and C. Is B not a relevant assumption (since we are more concerned about the details of the census) ?
Not only is doing the actual math completely needless for this question, I don't even see how your calculations help you realize that C is the assumption on which the argument depends. All you really need to do is to ask yourself "what is the argument assuming when it says that the picture painted by the census is accurate, even though some poor and some rich are not counted?" And the answer to that is that the argument assumes that the flawed counting is the same for both, so the final result is still accurate. Then go and find an answer choice that says that.

B goes too far - the rich and poor are brought as examples of places where the census fails to accurately sample reality, but there's no need to assume that ALL americans are either rich or poor - these are just examples.
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by badpoem » Wed Sep 07, 2011 5:14 am
Thank you Geva@MasterGMAT!

I hope I can hone my reasoning skills to match the way you deduced it. Thank you! :)
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by GmatKiss » Wed Sep 07, 2011 6:00 am
Thanks a ton Geva, i was blank before checking your explanation.
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by navami » Wed Sep 07, 2011 11:47 am
IMO C. B is close too
This time no looking back!!!
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