Critical Reasoning

I need explanation for answer-choices C), D) and E)

The Source is PowerScore CR Bible

premise: each region receives share in proportion to total population share...
Premise: % revenue received were decreased for Korva, but population increased...
conclusion?

A)doesn't matter.
B) it can be possible that population grew by larger %
C) let M and G each had x people and each's population increased by y% each.
and K initially had p and increased by q%. where y>q
now initial share = p/(p+2x)
new share = 100p+pq/ (100p+pq +200x+2xy)
new share - initial share = 100p+pq/ (100p+pq +200x+2xy) - P/(p+2x)
100pp + 2pqx - 100pp -ppq - 200xp -2pxy / denominator = 2px(q-y) - ppq - 200xp /D
q-y<0 and thus numerator <0 and thus new share < initial share

Thus c) is the answer. it will explain why its share decreased...


D) let k initial=10, final=11,
m,g: 10000 and final 10002
thus initial: 10/20010= 4.9975 and final: 11/20015=5.49
thus even if numerical increase was smallest, share increased. thus not valid

E)say m's population doubled and k's increased by 90% and g's only 1%... still k can get more share..

IMO C

Initially, I also chose C, but it the correct answer is E.

Wow! Wow! Wow!

I loved the question trap. (I was also trapped by C)

I forgot to see that in the Stimulus it only talk about the decrease in Korava only. It does not talk about how other two countries id grow. That means there is a possibility that Koravacould stand in the middle also.

Now E makes sense.

That is why I have started to read POWERSCORE two days back:) I have heard its a very good source to learn reasoning.

Good one!! Again was trapped with C..

-GK

awesome post.. very good question

Thanks....

Bek wrote:I need explanation for answer-choices C), D) and E)

The Source is PowerScore CR Bi


ble

This is indeed a good question. It is an LSAT question. It is from the December 1995 test, Logical reasoning section 2, # 24.

This is a good example of what I call "LSAT Math" there are a series of questions on the LSAT that deal with the difference between actual numbers and percentages. In this case, the actual number of citizens increased for KORVA. So that means simply that Korva/ Korva + Mitro + Guadar has to have decreased. The conclusion is that the numerator increased, but not by as much as the denominator.

It is not necessary that both M and G have increased by more than Korva only that one of them needs to have.

Another LSAT trick you can use is this: If answer A makes another answer correct you cannot choose A. In this case answer choice C makes choice E correct. Do you see it? Choice C says "The populations of Mitro and Guadar each increased by a percentage that exceeded the percentage by which the population of Korva increased." Well if it is true that they each increased more than Korva well choice E would then be forced to be correct. E "Korva's population grew by a smaller percentage than did the population of at least one of the other two autonomous regions."

Of course you are taking the GMAT and so this question will not translate exactly but you can learn from it. Anyway, it is a fun question I teach it a couple of times a year when I teach the LSAT.