BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Dwarf masked owl - 1000CR

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Legendary Member
Posts: 1261
Joined: Sun Sep 14, 2008 3:46 am
Thanked: 27 times
GMAT Score:570

Dwarf masked owl - 1000CR

by reply2spg » Sun Aug 08, 2010 10:41 am
The dwarf masked owl, a rare migratory bird of prey, normally makes its winter home on the Baja peninsula, where it nests in the spiny cactus. In fact, there are no other suitable nesting sites for the dwarf masked owl on the Baja peninsula. But a blight last spring destroyed all of the spiny cacti on the Baja peninsula. So unless steps are taken to reestablish the spiny cactus population, the dwarf masked owl will not make its home on the Baja peninsula this winter.

The argument depends on assuming which one of the following?

(A) No birds of prey other than the dwarf masked owl nest in the spiny cactus.
(B) If the Baja peninsula contains spiny cacti, then the dwarf masked owl makes its winter home there.
(C) On occasion the dwarf masked owl has been known to make its winter home far from its normal migratory route.
(D) The dwarf masked owl will not make its winter home on the Baja peninsula only if that region contains no spiny cacti.
(E) Suitable nesting sites must be present where the dwarf masked owl masked its winter home.

[spoiler]OA E, Does that mean that D is mentioned in passage?[/spoiler]
Sudhanshu
(have lot of things to learn from all of you)
Top
Source: — Critical Reasoning |
GMAT Instructor
Posts: 357
Joined: Wed Aug 12, 2009 8:31 pm
Thanked: 128 times
Followed by:7 members

by grockit_andrea » Sun Aug 08, 2010 11:16 am
reply2spg wrote:The dwarf masked owl, a rare migratory bird of prey, normally makes its winter home on the Baja peninsula, where it nests in the spiny cactus. In fact, there are no other suitable nesting sites for the dwarf masked owl on the Baja peninsula. But a blight last spring destroyed all of the spiny cacti on the Baja peninsula. So unless steps are taken to reestablish the spiny cactus population, the dwarf masked owl will not make its home on the Baja peninsula this winter.

The argument depends on assuming which one of the following?

(A) No birds of prey other than the dwarf masked owl nest in the spiny cactus.
(B) If the Baja peninsula contains spiny cacti, then the dwarf masked owl makes its winter home there.
(C) On occasion the dwarf masked owl has been known to make its winter home far from its normal migratory route.
(D) The dwarf masked owl will not make its winter home on the Baja peninsula only if that region contains no spiny cacti.
(E) Suitable nesting sites must be present where the dwarf masked owl masked its winter home.

[spoiler]OA E, Does that mean that D is mentioned in passage?[/spoiler]
This is a great example of a question where formal logic approaches actually work really well. The passage can be represented as follows:

DMO (Dwarf Masked Owl) winters on the Baja peninsula
DMO ==> nest in spiny cactus
Baja peninsula ==> no spiny cactus
No spiny cactus in Baha ==> no suitable nesting site for DMO
If no spiny cactus ==> no DMO

There's no link in that series of statements showing what the significance is of a suitable nesting site. We *assume* that the DMO must have a suitable nesting site. And so does the author: choice E establishes that link. Choice D actually twists the information in the passage and cannot be proven true. The "only if" in D is the problem; what if there was no food for the DMO on the Baja peninsula? Or what if some kind of toxic accident made it uninhabitable? The point is, there could be other reasons besides the lack of spiny cacti for the DMO not to make its winter home on the Baja peininsula, so the argument neither contains nor depends upon the statement in D.
Andrea A.
Grockit Tutor
https://www.grockit.com
Top
User avatar
Legendary Member
Posts: 1261
Joined: Sun Sep 14, 2008 3:46 am
Thanked: 27 times
GMAT Score:570

by reply2spg » Sun Aug 08, 2010 11:22 am
Thanks Andrea...
grockit_andrea wrote:
reply2spg wrote:The dwarf masked owl, a rare migratory bird of prey, normally makes its winter home on the Baja peninsula, where it nests in the spiny cactus. In fact, there are no other suitable nesting sites for the dwarf masked owl on the Baja peninsula. But a blight last spring destroyed all of the spiny cacti on the Baja peninsula. So unless steps are taken to reestablish the spiny cactus population, the dwarf masked owl will not make its home on the Baja peninsula this winter.

The argument depends on assuming which one of the following?

(A) No birds of prey other than the dwarf masked owl nest in the spiny cactus.
(B) If the Baja peninsula contains spiny cacti, then the dwarf masked owl makes its winter home there.
(C) On occasion the dwarf masked owl has been known to make its winter home far from its normal migratory route.
(D) The dwarf masked owl will not make its winter home on the Baja peninsula only if that region contains no spiny cacti.
(E) Suitable nesting sites must be present where the dwarf masked owl masked its winter home.

[spoiler]OA E, Does that mean that D is mentioned in passage?[/spoiler]
This is a great example of a question where formal logic approaches actually work really well. The passage can be represented as follows:

DMO (Dwarf Masked Owl) winters on the Baja peninsula
DMO ==> nest in spiny cactus
Baja peninsula ==> no spiny cactus
No spiny cactus in Baha ==> no suitable nesting site for DMO
If no spiny cactus ==> no DMO

There's no link in that series of statements showing what the significance is of a suitable nesting site. We *assume* that the DMO must have a suitable nesting site. And so does the author: choice E establishes that link. Choice D actually twists the information in the passage and cannot be proven true. The "only if" in D is the problem; what if there was no food for the DMO on the Baja peninsula? Or what if some kind of toxic accident made it uninhabitable? The point is, there could be other reasons besides the lack of spiny cacti for the DMO not to make its winter home on the Baja peininsula, so the argument neither contains nor depends upon the statement in D.
Sudhanshu
(have lot of things to learn from all of you)
Top
User avatar
Senior | Next Rank: 100 Posts
Posts: 82
Joined: Thu May 27, 2010 12:23 pm
Location: Newyork
Thanked: 2 times
Followed by:3 members

by selfmade » Sun Aug 08, 2010 11:28 am
I would pick E. I think you are down to two options here D and E

Lets look at the first line of the passage.

The dwarf masked owl normally makes its winter home on the Baja peninsula , where it nests in spiny cactus.

This statement only gives us information about the nests of owl in Baka peninsula, but does not tell us that spiny cactus is the reason why the owl makes the home on Baja peninsula. This means there are other reasons for owl to make its home in Baja peninsula.

X - The dwarf masked owl normally makes its winter home on the Baja peninsula
Y - not only because of spiny cactus

so X --- > Y

If you negate both sides

~ X ---- > `Y , you will end up at D .

(D) The dwarf masked owl will not make its winter home on the Baja peninsula only if that region contains no spiny cacti.

This is not an assumption but its inference.


The question asks about the assumption , which is correctly stated in E.
----------
Aiming for 780
Top
Junior | Next Rank: 30 Posts
Posts: 21
Joined: Fri Jul 16, 2010 6:56 am
Thanked: 2 times

by seshadrivyas » Sun Aug 08, 2010 11:15 pm
Can some one explain why it is not B. I thought that to be the answer when I read through.
My reasoning was that, to find the assumption in this question, we have to establish that the owl makes its winter home in Baja Peninsula if cacti are present. Only if this is established, can we conclude that efforts to restore cacti population will make the owls come to the peninsula.

If B were not to be true then the suggestion made by the author becomes irrelevant.

Can some one please help me on this?
Top
GMAT Instructor
Posts: 357
Joined: Wed Aug 12, 2009 8:31 pm
Thanked: 128 times
Followed by:7 members

by grockit_andrea » Mon Aug 09, 2010 10:57 am
seshadrivyas wrote:Can some one explain why it is not B. I thought that to be the answer when I read through.
My reasoning was that, to find the assumption in this question, we have to establish that the owl makes its winter home in Baja Peninsula if cacti are present. Only if this is established, can we conclude that efforts to restore cacti population will make the owls come to the peninsula.

If B were not to be true then the suggestion made by the author becomes irrelevant.

Can some one please help me on this?
B establishes that it's SUFFICIENT for spiny cacti to be present if the DMO is to make its home there; however, it doesn't establish that it's NECESSARY, which is what we need for the assumption here. Even if B were true, that's not to say that there couldn't be some other things that would cause the DMO to come to the Baja peninsula. This is where the formal logic comes in; B says "If there are spiny cacti ==> the DMO makes its winter home there." A correct representation of the necessary assumption (although still leaving out the idea of suitable nesting sites) would be "If the DMO makes its winter home on the Baja peninsula ==> there are spiny cacti there." This latter statement reverses the necessary and sufficient elements of B.
Andrea A.
Grockit Tutor
https://www.grockit.com
Top
User avatar
Community Manager
Posts: 1048
Joined: Mon Aug 17, 2009 3:26 am
Location: India
Thanked: 51 times
Followed by:27 members
GMAT Score:670

by arora007 » Wed Aug 11, 2010 9:55 am
reply2spg wrote:The dwarf masked owl, a rare migratory bird of prey, normally makes its winter home on the Baja peninsula, where it nests in the spiny cactus. In fact, there are no other suitable nesting sites for the dwarf masked owl on the Baja peninsula. But a blight last spring destroyed all of the spiny cacti on the Baja peninsula. So unless steps are taken to reestablish the spiny cactus population, the dwarf masked owl will not make its home on the Baja peninsula this winter.

The argument depends on assuming which one of the following?

(A) No birds of prey other than the dwarf masked owl nest in the spiny cactus.
(B) If the Baja peninsula contains spiny cacti, then the dwarf masked owl makes its winter home there.
(C) On occasion the dwarf masked owl has been known to make its winter home far from its normal migratory route.
(D) The dwarf masked owl will not make its winter home on the Baja peninsula only if that region contains no spiny cacti.
(E) Suitable nesting sites must be present where the dwarf masked owl masked its winter home.

[spoiler]OA E, Does that mean that D is mentioned in passage?[/spoiler]
This is a good problem.. i too read B and parked it as a probable answer... and when I read E i found it better...
https://www.skiponemeal.org/
https://twitter.com/skiponemeal
Few things are impossible to diligence & skill.Great works are performed not by strength,but by perseverance

pm me if you find junk/spam/abusive language, Lets keep our community clean!!
Top
Post new topic Post Reply
• Page 1 of 1