Critical Reasoning

Source: Beat The GMAT Practice Questions

Wolves can double their numbers every year. They do not do so, however, if the area in which they live is already full and the territory of each pack borders on the territory of other packs on all sides. Lone wolves, unable to establish a territory near their place of origin, disperse to a less desirable habitat and often are hunted by people.

Which of the following conclusions may be properly drawn from the information in the passage above?

A. The number of wolves in any area suitable for wolves may be predicted to quadruple in two years.
B. Wolves are ejected from the pack to wander singly as lone wolves when the number of wolves in the pack has doubled.
C. The amount of territory suitable for wolves has been diminishing in recent years as a result of human encroachment, with a resulting diminution in the wolf population.
D. Wolf hunting can continue at a moderate rate on the fringes of a good habitat for wolves without a decrease in the average yearly wolf population in that territory.
E. The wolf population density in a given area of wolf territory does not vary with the yearly rate of wolf reproduction.

E.

IMO: E

IMO: B

Can Dana give the OA?

Hey everyone,

The OA is D. Here's my explanation adapted from the official one in the Beat The GMAT Practice Questions:

So let's see how we break down this argument. We know that the wolf population of a certain area can double every year, but they won't necessarily do that if the territory is too crowded. Lone wolves who can't get their own territory will move to places that are not so good, where they may be hunted by people.

A is not correct because it's not necessarily true, as stated in our first premise: while they can double every year (they'd quadruple in two years), this may not happen because of territory issues.

B can be eliminated because we're explicitly told in the argument that lone wolves are "unable to establish a territory near their place of origin". This does not mean that they're expelled from the pack just because the pack has doubled - maybe some wolves are chased away from the pack before the number doubles...

While we may feel like C is right because we know it's true from experience, there's nothing in the argument to suggest human encroachment on the wolves' territory.

D is actually the correct answer here. Even if some wolves are hunted down by humans, since the pack can double every year, the loss of a few wolves will be offset by the birth of new wolves. Take an example: suppose you start out with a pack of 15 wolves in a certain territory. 7 of them became aggressive and they had to be hunted down. We're left with 15 - 7 = 8 wolves in the pack. It's a great loss, but by the end of the year the pack can double. So the new number of wolves will be 2*8 = 16 wolves, which is pretty close to 15.

E kindda contradicts the passage. If the wolves double every year in a certain territory that's not yet full, then the density gets bigger and bigger.

Hope you liked this one!

Are these questions really representative of GMAT? I have never seen any official question on these lines.

I'd say this is a really tough question - I remember seeing questions like this one in some LSAT sets.

DanaJ wrote:I'd say this is a really tough question - I remember seeing questions like this one in some LSAT sets.

Hi Dana ,
I thought we need to put on our blinders when we come across a conclusion related CR in GMAT i.e only derive based on content in the passage .. Isnt that true ? If yes , dont you think this conclusion is not really representative of GMAT q's?

Hey Deb,

Yes, you are right. But I think the conclusion is properly drawn here. Indeed, this is a rare question type in the GMAT (you don't see it as often as you see strengthen or weaken, for instance), but I'd say it's still pretty representative (if a bit on the tough side).

Dana ... I have a query

Firstly, good question, very representative of actual GMAT. Answer D could be reached easily with elimination.

BTG questions, who wrote these questions? Do they mirror GMAT questions in general?

How many questions are there for Verbal (category wise)?

Mohit

@mohit11: these questions were written by Brent Hanneson (for quant) and David Scarlise. You can read more about them by going to the website www.practice.beatthegmat.com. I've been going through them lately and feel that they are pretty representative of the GMAT in general. I've posted a few myself (you can check them out by looking up my latest posts).

For verbal, there are around 300 something questions, at least 100 per category (don't know the exact numbers though).

DanaJ wrote:@mohit11: these questions were written by Brent Hanneson (for quant) and David Scarlise. You can read more about them by going to the website www.practice.beatthegmat.com. I've been going through them lately and feel that they are pretty representative of the GMAT in general. I've posted a few myself (you can check them out by looking up my latest posts).

For verbal, there are around 300 something questions, at least 100 per category (don't know the exact numbers though).

Thanks Dana. You''re helpful as ever

Hi,
This was an awesome question.I am glad i won the free practice questions subscription.I could reach D after following a stringent criteria for elimination which is contray to what someone stated in this thread.
I hope this question is representative of most of the questions in the BTG Practice questions.
Can someone tell when did BTG come out with these practice questions.I thought BTG just brought them out this year.
What level should this question be?

DanaJ wrote:Hey everyone,

The OA is D. Here's my explanation adapted from the official one in the Beat The GMAT Practice Questions:

So let's see how we break down this argument. We know that the wolf population of a certain area can double every year, but they won't necessarily do that if the territory is too crowded. Lone wolves who can't get their own territory will move to places that are not so good, where they may be hunted by people.

A is not correct because it's not necessarily true, as stated in our first premise: while they can double every year (they'd quadruple in two years), this may not happen because of territory issues.

B can be eliminated because we're explicitly told in the argument that lone wolves are "unable to establish a territory near their place of origin". This does not mean that they're expelled from the pack just because the pack has doubled - maybe some wolves are chased away from the pack before the number doubles...

While we may feel like C is right because we know it's true from experience, there's nothing in the argument to suggest human encroachment on the wolves' territory.

D is actually the correct answer here. Even if some wolves are hunted down by humans, since the pack can double every year, the loss of a few wolves will be offset by the birth of new wolves. Take an example: suppose you start out with a pack of 15 wolves in a certain territory. 7 of them became aggressive and they had to be hunted down. We're left with 15 - 7 = 8 wolves in the pack. It's a great loss, but by the end of the year the pack can double. So the new number of wolves will be 2*8 = 16 wolves, which is pretty close to 15.

E kindda contradicts the passage. If the wolves double every year in a certain territory that's not yet full, then the density gets bigger and bigger.

Hope you liked this one!

Hi Dana , I have a doubt about the reasoning you used to zero on to D as the conclusion.The author talk of hunting only with regard to lone wolves who were thrown out of their territories.
WHEREAS
You talk of hunting that actually takes place in the woles territory and not outside ,less desirable territories.

Oh OK, it makes sense, but at the same time if the pack is not affected (because the hunting goes on the fringes and not on the pack's territory), then we're still good with the number of wolves, right?