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# dolphins

Author Message
VP
Joined: 09 Jul 2007
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11 Nov 2007, 16:12
Some species of dolphins find their prey by
echolocation; they emit clicking sounds and listen for
echoes returning from distant objects in the water.
Marine biologists have speculated that those same
clicking sounds might have a second function:
particularly loud clicks might be used by the dolphins
to stun their prey at close range through sensory

Which of the following, if discovered to be true,
would cast the most serious doubt on the correctness
of the speculation described above?

(A) Dolphins that use echolocation to locate distant
prey also emit frequent clicks at intermediate
distances as they close in on their prey.

(B) The usefulness of echolocation as a means of
locating prey depends on the clicking sounds
being of a type that the prey is incapable of
perceiving, regardless of volume.

(C) If dolphins stun their prey, the effect is bound to
be so temporary that stunning from far away,
even if possible, would be ineffective.

(D) Echolocation appears to give dolphins that use it
information about the richness of a source of food
as well as about its direction.

(E) The more distant a dolphin's prey, the louder the
echolocation clicks must be if they are to reveal
the prey's presence to the hunting dolphin.

OA is B

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Intern
Joined: 11 Nov 2007
Posts: 23

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11 Nov 2007, 19:31
(A) Dolphins that use echolocation to locate distant
prey also emit frequent clicks at intermediate
distances as they close in on their prey. - GIVEN PORTION OF TEXT DOES NOT TALKS ABOUT FREQUENCY OF CLICKS !!!

(B) The usefulness of echolocation as a means of
locating prey depends on the clicking sounds
being of a type that the prey is incapable of
perceiving, regardless of volume. -PASSAGE DOES NOT RELATE TO CAPABILITY OF PREY.

(C) If dolphins stun their prey, the effect is bound to
be so temporary that stunning from far away,
even if possible, would be ineffective. - EFFECT OF STUNNING IS ILLOGICAL.

(D) Echolocation appears to give dolphins that use it
information about the richness of a source of food
as well as about its direction. - RICHNESS OF FOOD ???

(E) The more distant a dolphin's prey, the louder the
echolocation clicks must be if they are to reveal
the prey's presence to the hunting dolphin. - YES..FARTHER...LOUD CLICK....CLOSER...SLOWER CLICK..IF THIS IS FOUND TRUE, IT WOULD CREATE MOST DOUBT ON THE SPECULATION MADE IN THE PASSAGE..

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Senior Manager
Joined: 09 Oct 2007
Posts: 463

Kudos [?]: 54 [0], given: 1

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11 Nov 2007, 22:09
I don't like any of the answers. I don't think B should be right, the question asks for something that weakens the speculation.

Dolphins locating prey by echolocation is not in doubt. It's presented as a fact. The speculation is related to the capability of the dolphins to use echolocation to stun their prey.

Kudos [?]: 54 [0], given: 1

CEO
Joined: 29 Mar 2007
Posts: 2554

Kudos [?]: 512 [0], given: 0

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11 Nov 2007, 22:40
Ravshonbek wrote:
Some species of dolphins find their prey by
echolocation; they emit clicking sounds and listen for
echoes returning from distant objects in the water.
Marine biologists have speculated that those same
clicking sounds might have a second function:
particularly loud clicks might be used by the dolphins
to stun their prey at close range through sensory

Which of the following, if discovered to be true,
would cast the most serious doubt on the correctness
of the speculation described above?

(A) Dolphins that use echolocation to locate distant
prey also emit frequent clicks at intermediate
distances as they close in on their prey.

(B) The usefulness of echolocation as a means of
locating prey depends on the clicking sounds
being of a type that the prey is incapable of
perceiving, regardless of volume.

(C) If dolphins stun their prey, the effect is bound to
be so temporary that stunning from far away,
even if possible, would be ineffective.

(D) Echolocation appears to give dolphins that use it
information about the richness of a source of food
as well as about its direction.

(E) The more distant a dolphin's prey, the louder the
echolocation clicks must be if they are to reveal
the prey's presence to the hunting dolphin.

OA is B

What is the source. I was down to B and E and picked E over B. I don't see how B is it.

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SVP
Joined: 28 Dec 2005
Posts: 1545

Kudos [?]: 179 [1], given: 2

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12 Nov 2007, 05:41
1
KUDOS
i picked B. Passage talks about sensory overload on the prey .... if it is shown that the clicks emitted are such that prey cant hear them anyways, then that shoots down the theory of sensory overload. If they cant hear it, they wont be overloaded

Kudos [?]: 179 [1], given: 2

Director
Joined: 09 Aug 2006
Posts: 754

Kudos [?]: 254 [0], given: 0

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12 Nov 2007, 05:53
Ravshonbek wrote:
Some species of dolphins find their prey by
echolocation; they emit clicking sounds and listen for
echoes returning from distant objects in the water.
Marine biologists have speculated that those same
clicking sounds might have a second function:
particularly loud clicks might be used by the dolphins
to stun their prey at close range through sensory

Which of the following, if discovered to be true,
would cast the most serious doubt on the correctness
of the speculation described above?

(A) Dolphins that use echolocation to locate distant
prey also emit frequent clicks at intermediate
distances as they close in on their prey.
So? Useless.

(B) The usefulness of echolocation as a means of
locating prey depends on the clicking sounds
being of a type that the prey is incapable of
perceiving, regardless of volume.
Correct: States that the usefulness of this technique depends on the type of sound and not on the volume of sound as stated in the stem.

(C) If dolphins stun their prey, the effect is bound to
be so temporary that stunning from far away,
even if possible, would be ineffective.
Out of scope. The stem is talking about close-range prey.

(D) Echolocation appears to give dolphins that use it
information about the richness of a source of food
as well as about its direction.
Out of scope.

(E) The more distant a dolphin's prey, the louder the
echolocation clicks must be if they are to reveal
the prey's presence to the hunting dolphin.
So? What does this have to do with stunning close-range prey?

OA is B

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VP
Joined: 09 Jul 2007
Posts: 1098

Kudos [?]: 141 [0], given: 0

Location: London

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12 Nov 2007, 08:59
highlight below the answer choices for the OA.

Thanks guys.

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Intern
Joined: 11 Nov 2007
Posts: 23

Kudos [?]: 3 [1], given: 0

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12 Nov 2007, 09:28
1
KUDOS
what's the OA guys ???

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Senior Manager
Joined: 09 Oct 2007
Posts: 463

Kudos [?]: 54 [1], given: 1

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12 Nov 2007, 10:12
1
KUDOS
ravi, it's right under the last answer choice (E) in the first post. it's in white type, so it's hard to see. Try hightlighting it if you can't see it. It's B, btw.

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Director
Joined: 25 Aug 2007
Posts: 927

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19 May 2010, 01:12
I marked B.

We need to show a weakness in the speculation. So, we should find the vulnerable assumption that -to stun their prey, dolphins may use some other mechanism rather than the particular loud clicks.

This is what B says. E rather supports the speculation rather than weakens it.

Ravshonbek wrote:
Some species of dolphins find their prey by
echolocation; they emit clicking sounds and listen for
echoes returning from distant objects in the water.
Marine biologists have speculated that those same
clicking sounds might have a second function:
particularly loud clicks might be used by the dolphins
to stun their prey at close range through sensory

Which of the following, if discovered to be true,
would cast the most serious doubt on the correctness
of the speculation described above?

(A) Dolphins that use echolocation to locate distant
prey also emit frequent clicks at intermediate
distances as they close in on their prey.

(B) The usefulness of echolocation as a means of
locating prey depends on the clicking sounds
being of a type that the prey is incapable of
perceiving, regardless of volume.

(C) If dolphins stun their prey, the effect is bound to
be so temporary that stunning from far away,
even if possible, would be ineffective.

(D) Echolocation appears to give dolphins that use it
information about the richness of a source of food
as well as about its direction.

(E) The more distant a dolphin's prey, the louder the
echolocation clicks must be if they are to reveal
the prey's presence to the hunting dolphin.

OA is B

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VP
Joined: 16 Jul 2009
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19 Jun 2010, 10:42
pmenon wrote:
i picked B. Passage talks about sensory overload on the prey .... if it is shown that the clicks emitted are such that prey cant hear them anyways, then that shoots down the theory of sensory overload. If they cant hear it, they wont be overloaded

I think that is assuming to much.
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Manager
Joined: 16 Jun 2010
Posts: 181

Kudos [?]: 99 [0], given: 5

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31 Jul 2010, 15:35
We need to find an answer that weakens the speculation,
A - Strengthens the speculation - By using frequent clicks on approaching the prey, it can imply that dolphin uses it to stun the prey.
B - Weakens the speculation - The statement states that the cliks are such that the prey cannot hear them, so if the prey cannot hear them then they wont be stunned by them.
C- Supports the wrong speculation - It says that the dolphin might be able to stun the prey from far away, however the speculation clearly states that the stunning by dolphins is done from close quarters.
D- Definitely Out of scope.
E- Out of scope as it talks about finding the prey rather than stunning it.
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Manager
Joined: 16 Oct 2011
Posts: 128

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15 Nov 2011, 19:11
ravi_taneja_1977 wrote:
(A) Dolphins that use echolocation to locate distant
prey also emit frequent clicks at intermediate
distances as they close in on their prey. - GIVEN PORTION OF TEXT DOES NOT TALKS ABOUT FREQUENCY OF CLICKS !!!

(B) The usefulness of echolocation as a means of
locating prey depends on the clicking sounds
being of a type that the prey is incapable of
perceiving, regardless of volume. -PASSAGE DOES NOT RELATE TO CAPABILITY OF PREY.

(C) If dolphins stun their prey, the effect is bound to
be so temporary that stunning from far away,
even if possible, would be ineffective. - EFFECT OF STUNNING IS ILLOGICAL.

(D) Echolocation appears to give dolphins that use it
information about the richness of a source of food
as well as about its direction. - RICHNESS OF FOOD ???

(E) The more distant a dolphin's prey, the louder the
echolocation clicks must be if they are to reveal
the prey's presence to the hunting dolphin. - YES..FARTHER...LOUD CLICK....CLOSER...SLOWER CLICK..IF THIS IS FOUND TRUE, IT WOULD CREATE MOST DOUBT ON THE SPECULATION MADE IN THE PASSAGE..

Hi,
E -> Slower Click => Closer - Is not specified. Doesn't speak about the closer range. There is a small assumption in this inference. B gets an edge here.

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Current Student
Joined: 06 Sep 2013
Posts: 1978

Kudos [?]: 719 [0], given: 355

Concentration: Finance

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14 Oct 2013, 06:01
devashish wrote:
We need to find an answer that weakens the speculation,
A - Strengthens the speculation - By using frequent clicks on approaching the prey, it can imply that dolphin uses it to stun the prey.
B - Weakens the speculation - The statement states that the cliks are such that the prey cannot hear them, so if the prey cannot hear them then they wont be stunned by them.
C- Supports the wrong speculation - It says that the dolphin might be able to stun the prey from far away, however the speculation clearly states that the stunning by dolphins is done from close quarters.
D- Definitely Out of scope.
E- Out of scope as it talks about finding the prey rather than stunning it.

Agree with you. Great explanation.
This is the exact reason why B is the correct choice

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Manager
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23 May 2014, 05:10
1
KUDOS
fact: Dolphins use clicking noises to LOCATE their prey.
Conclusion: Dolphins use these same clicks to STUN their prey.
To weaken the conclusion, the correct answer must BREAK THE LINK between the use of echolocation to LOCATE prey and the use of it to STUN prey.

The USEFULNESS OF ECHOLOCATION AS A MEANS OF LOCATING PREY depends on the clicking sounds being of a type that THE PREY IS INCAPABLE OF PERCEIVING, regardless of volume.
The prey CANNOT BE STUNNED by clicks that it is INCAPABLE OF PERCEIVING, invalidating the conclusion that the dolphins use the clicks to stun their prey.

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Intern
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23 Jun 2017, 07:13
I filtered out all the options that talks about "distant/far away". This leaves us only with A and B. Since A does not weaken the argument. Hence, answer is B.

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Re: dolphins   [#permalink] 23 Jun 2017, 07:13
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