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Koalas in Queensland (Knewton Prep)

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Koalas in Queensland (Knewton Prep)

by RadiumBall » Wed Mar 30, 2011 8:57 pm
Koalas in Queensland, Australia, have a much larger "home range" of trees than do koalas in other regions of the Australian continent. The reason for this behavior is probably that the eucalyptus trees in Queensland do not bear as many leaves, which are the staple of a koala's diet, in Queensland than they do in other regions, and the relative scarcity of food requires the koalas to expand their range in order to find enough leaves on which to survive.

Which of the following, if true, most helps to confirm the explanation above?


(A) A small percentage of koalas in Queensland have "home ranges" that are almost five times as large as the home ranges of koalas that reside in other regions of Australia.
(B) Koalas have smaller "home ranges" in areas where the amount of annual rainfall allows eucalyptus trees to bloom more prosperously than in areas where rainfall is relatively scarce.
(C) During the September mating season, koalas require significantly more eucalyptus leaves per day from their "home range" of trees than they do during any other part of the year.
(D) At times, koalas in Queensland spend weeks eating leaves off of a single eucalyptus tree without completely defoliating the tree.
(E) Koalas have extremely slow metabolic rates, allowing them to survive on significantly less food than most other creatures of the same size.
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by AIM GMAT » Thu Mar 31, 2011 12:01 am
Again confused with A and B.

(A) A small percentage of koalas in Queensland have "home ranges" that are almost five times as large as the home ranges of koalas that reside in other regions of Australia.
(B) Koalas have smaller "home ranges" in areas where the amount of annual rainfall allows eucalyptus trees to bloom more prosperously than in areas where rainfall is relatively scarce.

IMO A.But B doesnt talk about Queensland so eliminating it .

Whats the OA ?
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by RadiumBall » Thu Mar 31, 2011 12:41 am
Even I was confused between A and B. I too selected A and OA is B but again I doubt the question itself so I am not going to break my head on this.

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by AIM GMAT » Thu Mar 31, 2011 12:48 am
RadiumBall wrote:Even I was confused between A and B. I too selected A and OA is B but again I doubt the question itself so I am not going to break my head on this.

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Is there any official explanation given with the CR , i mean just want to know on what basis they prefer B over A .
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by RadiumBall » Thu Mar 31, 2011 1:27 am
Here is the explanation:

The argument that koalas in Queensland have larger "home ranges" is based on the evidence that eucalyptus trees in Queensland bear fewer leaves, leaves that are the staples of koalas' diets. Thus, the argument concludes that koalas need to expand their range in order to gain exposure to more leaves. The best answer will provide evidence that would confirm this explanation.

Choice B names a scenario in which the trees bear more leaves. The cause of the koalas' large ranges, trees with few leaves, is eliminated. Because the koalas display smaller ranges when the cause is eliminated, there is evidence that this cause does in fact contribute to the koalas' large ranges. Any proof that the supposed cause, few leaves, does in fact contribute to the result-koalas displaying large ranges-would help confirm the explanation, and thus choice B is the best answer.

Choice A takes the phenomenon mentioned in the argument even further: that this narrow group's "home ranges" are extremely large does not provide any confirmation to the explanation that these large ranges are due to a lack of eucalyptus leaves.
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by AIM GMAT » Thu Mar 31, 2011 1:45 am
Yeah absolutely i had that as second thought , A repeats the same what is said in the argument and adds a evidence to it , but B states the reason for scant leaves .

Tricky , lesson learned , read like detective . :)
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by RadiumBall » Thu Mar 31, 2011 3:05 am
@AIM GMAT:
Can you please explain what you understood...because I still don't agree with B...
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by AIM GMAT » Thu Mar 31, 2011 3:22 am
RadiumBall wrote:@AIM GMAT:
Can you please explain what you understood...because I still don't agree with B...
Yeah sure .. the explanation follows :-

PREMISE 1 : Koalas in Queensland, Australia, have a much larger "home range" of trees than do koalas in other regions of the Australian continent.

PREMISE 2 : The reason for this behavior is probably that the eucalyptus trees in Queensland do not bear as many leaves, which are the staple of a koala's diet, in Queensland than they do in other regions, and the relative scarcity of food requires the koalas to expand their range in order to find enough leaves on which to survive

Now the second premise states that leaves are less on each tree , so supporting evidence should site something about why leaves are less , some reason concerning this fact.So now option A repeates the same thing given in argument that "home range" is large and it also gives the extent by which it is large as compared to other regions . So thats already told , we need some extra knowledge about why is home range large or why leaves are scant . So option B gives us that reason which in turn supports argument better than option A does.

Hope i havent made it more complicated , let me know if any portion is confusing , or if i can add some more reasoning . :)
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by fitzgerald23 » Thu Mar 31, 2011 6:59 am
AIM GMAT wrote:Yeah absolutely i had that as second thought , A repeats the same what is said in the argument and adds a evidence to it , but B states the reason for scant leaves .

Tricky , lesson learned , read like detective . :)
This is the key to eliminating A. You have to always read both the passage and question very carefully. The question wants confirmation of the explanation. All A does is give you the information already in the passage. That does not add anything to his explanation of why it occurs.
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by imonline » Fri Apr 01, 2011 4:22 am
IMO B
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by force5 » Sun Apr 03, 2011 2:25 pm
yes A and B are close but i'd mark B for similar reasons.. A is just reinstating the premise already mentioned.
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