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911-HELP!! Percent, Numbers CR

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911-HELP!! Percent, Numbers CR

by kanha81 » Wed Apr 15, 2009 1:51 pm
Grateful, if anyone can help explain/dissect the Percent, Numbers, Probability, Average Questions. I would be more interested in learning the tricks to correctly & quickly identify the errors in the answers choices to reach the required result.

Please HELP! Does anyone have a specific STRATEGY that they follow when handling the following type of questions? Any HELP is a GREAT help. This THREAD can prove fruitful to lot of us like me who has an issue or difficulty in comprehending and dissecting such questions.

In 1980, Country A had a per capita gross domestic
product (GDP) that was $5,000 higher than that of
the European Economic Community. By 1990, the
difference, when adjusted for inflation, had increased
to $6,000. Since a rising per capita GDP indicates a
rising average standard of living, the average
standard of living in Country A must have risen
between 1980 and 1990.

Which one of the following is an assumption on
which the argument depends?

(A) Between 1980 and 1990, Country A and the
European Economic Community
experienced the same percentage increase in
population.

(B) Between 1980 and 1990, the average standard
of living in the European Economic
Community fell.

(C) Some member countries of the European
Economic Community had, during the
1980s, a higher average standard of living
than Country A.

(D) The per capita GDP of the European Economic
Community was not lower by more than
$1,000 in 1990 than it had been in 1980.

(E) In 1990, no member country of the European
Economic Community had a per capita GDP
higher than that of Country A.
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by mbadrew » Wed Apr 15, 2009 2:50 pm
IMO the answer is B. The most logical explanation I can come up with is, when you are required to analyze a statistical assumption, then you should look for a statistical premise. The conclusion states that the GDP of country A rose from $5000-$6000 from 1980-1990. So, therefore the standard of living for country A must have risen. If you look at the answer choices, the only choice that you can consider a premise, and which is not part of the argument is choice B.

Let us know the OA. This is a tough one I'll say. I'd like to hear it from the experts.

thanks
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by sg1928 » Wed Apr 15, 2009 3:24 pm
mbadrew wrote:IMO the answer is B. The most logical explanation I can come up with is, when you are required to analyze a statistical assumption, then you should look for a statistical premise. The conclusion states that the GDP of country A rose from $5000-$6000 from 1980-1990. So, therefore the standard of living for country A must have risen. If you look at the answer choices, the only choice that you can consider a premise, and which is not part of the argument is choice B.

Let us know the OA. This is a tough one I'll say. I'd like to hear it from the experts.

thanks
Andrew
IMO d d is a right assumption bcos this clearly implies rise in the per capita GDP for country a
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by mikeCoolBoy » Wed Apr 15, 2009 8:44 pm
IMO D.

Argument: Because the difference between (GDP) of A and EEC is bigger in 1990 than in 1980, the author concludes that GDP of country A must have risen. This is true as long as GDP of EEC has risen as well.


D says that the difference between the GDP in 1980 and GDP in 1990 is not lower by more than 1000, so at least the GDP has risen 1000.

I hope this helps
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by lunarpower » Wed Apr 15, 2009 9:47 pm
the first thing that's conspicuous about this problem is that it's a "find the assumption" problem.

remember that you're looking for REQUIRED ASSUMPTIONS.

here's a very useful criterion to use in these problems:
try REVERSING putative assumptions and see the effect on the argument.
if you REVERSE A REQUIRED ASSUMPTION, the ARGUMENT SHOULD BECOME INVALID.

let's try this with choice (d):
reverse the assumption: this would mean that the gdp of the entire community WAS lower by more than $1000 in 1990.
therefore, the standard of living in country A went from
ORIGINAL EEC STANDARD + 5000
to
(ORIGINAL EEC STANDARD MINUS MORE THAN 1000) + 6000
the second of these is less than the first, so the argument falls apart.
therefore, this is the correct assumption.
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by lunarpower » Wed Apr 15, 2009 10:00 pm
also:

you won't be able to memorize everything that you'll ever need in order to solve any quantitative passage - there's too much variety for that to be feasible - but here are some concrete pieces of advice:

* notice distinctions between things.
your DEFAULT orientation should be something like "any 2 things should be considered completely different, unless i find EXPLICIT EVIDENCE that they are related."
- for instance, in this problem, nothing is ever mentioned about percentages. therefore, you should just assume that percentages have nothing to do with anything in the problem, unless there's evidence that they do (which there isn't). same thing for the standards of living of individual member countries of the EEC, which are not mentioned, nor indirectly alluded to, in the passage.

* be especially wary of conflating numerical figures with percents, fractions, or proportions.
- probably the single most common quantitative trap is the "let's pretend that percentages and absolute figures are the same" thing. remember that you can only relate percents/fractions/proportions to absolute figures if the underlying base amounts (i.e., the "whole" amounts, on which the percents/fractions/proportions are based) are the same. in other words, 50% of X isn't necessarily bigger than 30% of Y, but 50% of X is definitely bigger than 30% of Y.
yes, i know that's not true for negative numbers, but critical reasoning passages don't involve negative numbers.
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by lunarpower » Wed Apr 15, 2009 10:02 pm
and especially:

WHEN A PASSAGE PRESENTS QUANTITATIVE INFORMATION,
ALWAYS, ALWAYS, ALWAYS MAKE A CHART, TABLE, OR GRAPH.
always.

in this case, the fact that choice (d) is correct would've become substantially more clear, and easier to understand, had you made some type of chart.

even if you don't diagram / take notes on ANY other species of critical reasoning problem, you should ALWAYS put quantitative data into a chart, table, or graph.

think about it: imagine if the stats on the sports page were in paragraph form. it'd be ridiculous! it would take you several minutes just to, say, read the baseball standings.
that's what you're doing to yourself every time you solve a quantitative passage without making a table, graph, or chart.
proceed accordingly.
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by mbadrew » Thu Apr 16, 2009 7:29 am
lunarpower wrote:the first thing that's conspicuous about this problem is that it's a "find the assumption" problem.

remember that you're looking for REQUIRED ASSUMPTIONS.

here's a very useful criterion to use in these problems:
try REVERSING putative assumptions and see the effect on the argument.
if you REVERSE A REQUIRED ASSUMPTION, the ARGUMENT SHOULD BECOME INVALID.

let's try this with choice (d):
reverse the assumption: this would mean that the gdp of the entire community WAS lower by more than $1000 in 1990.
therefore, the standard of living in country A went from
ORIGINAL EEC STANDARD + 5000
to
(ORIGINAL EEC STANDARD MINUS MORE THAN 1000) + 6000
the second of these is less than the first, so the argument falls apart.
therefore, this is the correct assumption.
Ron,

Can you explain this using a chart system that you've mentioned.

I'm still not clear with the explanation.

thanks
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by kanha81 » Thu Apr 16, 2009 10:13 am
lunarpower wrote:also:

some concrete pieces of advice:

* notice distinctions between things.
your DEFAULT orientation should be something like "any 2 things should be considered completely different, unless i find EXPLICIT EVIDENCE that they are related."
- for instance, in this problem, nothing is ever mentioned about percentages. therefore, you should just assume that percentages have nothing to do with anything in the problem, unless there's evidence that they do (which there isn't). same thing for the standards of living of individual member countries of the EEC, which are not mentioned, nor indirectly alluded to, in the passage.

* be especially wary of conflating numerical figures with percents, fractions, or proportions.
- probably the single most common quantitative trap is the "let's pretend that percentages and absolute figures are the same" thing. remember that you can only relate percents/fractions/proportions to absolute figures if the underlying base amounts (i.e., the "whole" amounts, on which the percents/fractions/proportions are based) are the same. in other words, 50% of X isn't necessarily bigger than 30% of Y, but 50% of X is definitely bigger than 30% of Y.
yes, i know that's not true for negative numbers, but critical reasoning passages don't involve negative numbers.
This makes lot of sense now in understanding the correct and incorrect answer types to the quantitative type questions.
lunarpower wrote:and especially:

WHEN A PASSAGE PRESENTS QUANTITATIVE INFORMATION,
ALWAYS, ALWAYS, ALWAYS MAKE A CHART, TABLE, OR GRAPH.
always.

in this case, the fact that choice (d) is correct would've become substantially more clear, and easier to understand, had you made some type of chart.

even if you don't diagram / take notes on ANY other species of critical reasoning problem, you should ALWAYS put quantitative data into a chart, table, or graph.
I will once again attempt to extrapolate the information from the CR into Table or Chart, but in the process of doing so, I usually get entangled into the "whole/parts" and end up more confused than before. I certainly need more rigorous practice.

All in all, thank you Ron for the awesome pointers. This will indeed help.
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by nervesofsteel » Fri Apr 17, 2009 1:26 am
my two cents for the prob

A - B = 5000
New A-B = 6000

New, can be possible in below cases..

either A is increased , B is constant
or B is decreased when A is constant
Or both A and B increase but increase in A is more than increase in B


Thus assumption is 1) B has not decreased by more than 1000 as compared to A otherwise the difference between A and B will become more than 6000...
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by mbadrew » Fri Apr 17, 2009 6:40 am
nervesofsteel wrote:my two cents for the prob

A - B = 5000
New A-B = 6000

New, can be possible in below cases..

either A is increased , B is constant
or B is decreased when A is constant
Or both A and B increase but increase in A is more than increase in B


Thus assumption is 1) B has not decreased by more than 1000 as compared to A otherwise the difference between A and B will become more than 6000...
Yes, this makes sense. I finally figured it out that one variable has to be constant. I was just getting confused with the wording.

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by ManSab » Fri Apr 17, 2009 10:46 am
Why not A?

Population is the prime factor for GDP growth.
If the population for both A and B is same,and country A GDP is more than country B---> This means
Living standard of the people in country A is more than people of country B.

Please correct me if I am wrong.

Thanks
Sami
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by mbadrew » Fri Apr 17, 2009 1:25 pm
ManSab wrote:Why not A?

Population is the prime factor for GDP growth.
If the population for both A and B is same,and country A GDP is more than country B---> This means
Living standard of the people in country A is more than people of country B.

Please correct me if I am wrong.

Thanks
Sami
Sami,

Let's analyze the conclusion, " Since a rising per capita GDP indicates a
rising average standard of living, the average standard of living in Country A must have risen between 1980 and 1990". Now A states that the population of both countries increased. If that was the case then the difference will still be $5000 and not $6000. For example if country A has 10 people and country B has 10 people and difference in per capita GDP is $5000 to begin with, then if the population of bother countries increased, for example country A=12 people, country B= 12 people, the per capita will not rise, rather it'll remain constant or proportionately decrease, but not reflecting change in proportion for both countries.

I hope this helps.
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by ManSab » Sun Apr 19, 2009 3:54 pm
Thank you mbadrew for beaking it down.
I over looked this point.
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by EricKryk » Sun Apr 19, 2009 8:15 pm
mbadrew wrote:
Sami,

Let's analyze the conclusion, " Since a rising per capita GDP indicates a
rising average standard of living, the average standard of living in Country A must have risen between 1980 and 1990". Now A states that the population of both countries increased. If that was the case then the difference will still be $5000 and not $6000. For example if country A has 10 people and country B has 10 people and difference in per capita GDP is $5000 to begin with, then if the population of bother countries increased, for example country A=12 people, country B= 12 people, the per capita will not rise, rather it'll remain constant or proportionately decrease, but not reflecting change in proportion for both countries.

I hope this helps.
It does help. thank you. What do you use to study CR?
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