Critical Reasoning

Given the question is a MUST BE TRUE/Inference one, choice E can be challenged in the same way that C has been challenged in the book - The CR Bible.

Here are 2 assumptions embedded in the both answers C and E;

1. The ratio of population in the 3 three regions is 1 ( the mindset of the test maker seems to be an even distribution of pop among the 3 regions) and
2. % increase. The difference btw the region's percentage increase will also be a determinant on the results. Korva's pop increased by a smaller percentage than those of the other region.

As an illustration, It makes a difference when the ratio of the population of Korva:Mitro: Guardar is 1:1:1 or 100:1:2 with a % increase of say K - 2% M - 0% and G - 50%. The Revenue share may vary greatly depending on the set of assumed pop size and realtive pop % increase.In a nutshell, both answers can be stretched to fit one's argument.

Because the conclusion must be drawn from the info provided ONLY in the stimulus, both answers C and E seem to be halfway true and draw on evidence not implicitly or explicitly stated in the Stimulus. Please help. Thank you!

The second assumption that you mention:

. The ratio of population in the 3 three regions is 1 ( the mindset of the test maker seems to be an even distribution of pop among the 3 regions)

is unwarranted. The answer choice is built like that to make it easier for calculations, but this is no way an assumption, it's just something they use to help you understand in a numerical format.

The revenue share may indeed vary greatly, but what does this "greatly" mean? We're not interested in actual numbers, but the relationships between them. Let me give you an example: say the share of one region was 50% last year and the share of another was 3%. If the first region grew to 53% of the total population but the second grew to 7%, then we have a greater percentage increase in the second region. However, in this particular case, it's obvious that the number of people in the second region is far below that of that from the first region.

Thanks Dana for the prompt response.

Choice E is somehow not precise. I'll attempt to use example to prove that it can contravene the facts on the stimulus.

Facts on the stimulus: Last year, the percentage of federal revenues Korva received for its share decreased somewhat even though the population survey on which the revenue-sharing was based showed that Korva's population had increased.

Choice E is halfway true as there are many possibilities that fit the facts above , however, there are afew instances when choice E presents a possibility that contradicts the stimulus. Here is an example below.

Regions --------------------Korva--------------Mitro---------------Guadar
Population Size -------------- 50m -------------- 45m -------------- 5m
Revenue Share -------------- 0.5-------------- 0.45-------------- 0.05

% Increase -------------- 1% ----------------- 0% -------------- 2%
New pop size-------------- 50.5m -------------- 45m -------------- 5.1m
Revenue share -------------- 0.502 --------------0.447-------------- 0.051

So one of the interpretation of choice E contradicts the stimulus as seen above. Please explain why it should still be the correct answer. Thanks for your continued help.

Haaress wrote:Thanks Dana for the prompt response.

Choice E is somehow not precise. I'll attempt to use example to prove that it can contravene the facts on the stimulus.

Facts on the stimulus: Last year, the percentage of federal revenues Korva received for its share decreased somewhat even though the population survey on which the revenue-sharing was based showed that Korva's population had increased.

Choice E is halfway true as there are many possibilities that fit the facts above , however, there are afew instances when choice E presents a possibility that contradicts the stimulus. Here is an example below.

Regions --------------------Korva--------------Mitro---------------Guadar
Population Size -------------- 50m -------------- 45m -------------- 5m
Revenue Share -------------- 0.5-------------- 0.45-------------- 0.05

% Increase -------------- 1% ----------------- 0% -------------- 2%
New pop size-------------- 50.5m -------------- 45m -------------- 5.1m
Revenue share -------------- 0.502 --------------0.447-------------- 0.051

So one of the interpretation of choice E contradicts the stimulus as seen above. Please explain why it should still be the correct answer. Thanks for your continued help.

Your job is to realize why (e) must be true if Korva's revenue share has fallen, not to prove that Korva's revenue share has fallen if (e) is true


If Daisy is a normal horse, we can infer that Daisy has four legs, even though not everything with 4 legs is a horse.

Thanks Kevin. I am getting a little more acquainted with it now but here is one final basic question.

Does K's population grew by a smaller % than did the population of at least one of the 2 other regions mean that the population (number) grew more in ( Mitro + Guadar ) than it did in Korva or the percentage increased in at least one of the 2 regions more than it did in Korva.

Thanks again!

I'd say it's the second option you mention: the percentage increased in at least one of the two regions more than in K.

Hi Testuv what is the problem with D here?

Don't confuse numbers with proportions: it may be that K's population grew the most in absolute terms, but the least in percentage terms.

Not clear kevin....can you please elaborate this question in more details...

Testluv wrote:sure.


................Before........After
Korvo........30...............40

Mitro.........30................30

Guadar.....40...............130

Total.........100.............200

As you can see even though Korvo's population increased, it's share of the total went down even though Guadar is the only other country that has experienced an increase.

Hey Testluv, I have one example to prove answer E wrong

let's see

......................... Now ......................... % increase ..........................After

Korvo........................ 1000.............................. 10 ................................... 1100



Mitro ..........................100................................. 5 .......................................105


Guardar....................... 10.................................20 ........................................12


To total.......................1110 ..........................................................................1217


We have: share of Korva population now: 1000/1110 = 0.9009009
share of Korva population after: 1100/1217 = 0.903862

From above example, if E true, there can be case in which share of Korva population increase.

ssgmatter wrote:Not clear kevin....can you please elaborate this question in more details...

Imagine a country with two regions, A and B.
A has a population of 9 million and B a population of 1 million. Thus 90% of the people in the country live in A.

If A's population were to increase by 2 million (22%) and B's by 1 million (100% increase), less than 90% of the country's increased population would be living in A. (11 of the 13 million people live in A, about 85% of the total)

Thus it is possible that a region that sees the greatest increase in population in absolute terms actually experiences a descrease in its share of the total population.

Guys,

can someone please explain why C is wrong. My understaning is that in a must be true the answer cannot be false no matter what.

E can be proven false; however I tried and could not make C False.

I am attaching a spreadsheet laying down choices C and E, will really appreciate if someone can explain where am I going wrong.

Thanks,

vineetbatra wrote:Guys,

can someone please explain why C is wrong. My understaning is that in a must be true the answer cannot be false no matter what.

E can be proven false; however I tried and could not make C False.

I am attaching a spreadsheet laying down choices C and E, will really appreciate if someone can explain where am I going wrong.

Thanks,

Your job is not to show that if E is true, K's share of the revenues has fallen. Rather, you should realize that if K's share of the revenue has fallen, E must be true

Thanks Kevin, I thihnk I got it now.

This is a very good problem.

This is from Power Score LSAT LR [GMAT CR] Bible
Actual Source: December 1995 LSAT, Section 2, #24

Thanks Testluv for explanation.