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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
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this is a weaken question so we have to determine the conclusion and premises first.

the conclusion of this argument is named as the speculation - that the clicking sounds might stun prey through sensory overload.
the premise is that other toothed whales stun their prey with clicks.

To weaken an argument, you generally bring in new, relevant information, that shows that the conclusion is not necessarily true. So here we need to show that the clicking sounds are not used to stun. so an answer choice has to provide information that would mean this.
pavan2185 wrote:


A. Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.[color=#ff0000]The fact that they emit clicks as intermediate distances does not give us information about the ability to stun prey[/color]
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.This is the correct answer because if the clicks can only be useful if the prey cannot perceive them then this means that the prey could not be stunned by sensory overload by them - making it unlikely that they use the clicks for both echolocation and to stun their 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.the conclusion does not depend on how long the prey is stunned, only that they are stunned by the clicks so this is irrelevant
D. Echolocation appears to give dolphins information about the richness of a source of food as well as about its direction.the fact that the clicks can give more information does not mean that they cannot also stun their prey so this does not weaken the argument
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.The volume of the clicks is not mentioned in relation to stunning a prey, only in revealing it and no information is given that they could not use these loud clicks to stun as well so this does not weaken.
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
B it is, as the speculation by marine biologist is "particularly loud clicks might be used by
the dolphins to stun their prey at close range through sensory overload";

B says "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." if prey cannot perceive it how can the sensory overload take place ?
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
BeckyRobinsonTPR wrote:
this is a weaken question so we have to determine the conclusion and premises first.

the conclusion of this argument is named as the speculation - that the clicking sounds might stun prey through sensory overload.
the premise is that other toothed whales stun their prey with clicks.

To weaken an argument, you generally bring in new, relevant information, that shows that the conclusion is not necessarily true. So here we need to show that the clicking sounds are not used to stun. so an answer choice has to provide information that would mean this.
pavan2185 wrote:


A. Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.[color=#ff0000]The fact that they emit clicks as intermediate distances does not give us information about the ability to stun prey[/color]
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.This is the correct answer because if the clicks can only be useful if the prey cannot perceive them then this means that the prey could not be stunned by sensory overload by them - making it unlikely that they use the clicks for both echolocation and to stun their 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.the conclusion does not depend on how long the prey is stunned, only that they are stunned by the clicks so this is irrelevant
D. Echolocation appears to give dolphins information about the richness of a source of food as well as about its direction.the fact that the clicks can give more information does not mean that they cannot also stun their prey so this does not weaken the argument
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.The volume of the clicks is not mentioned in relation to stunning a prey, only in revealing it and no information is given that they could not use these loud clicks to stun as well so this does not weaken.


What is the level of this question, according to your estimation?
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Re: dolphins [#permalink]
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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.

Answer choice B breaks the link between the two:

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.

so answer is B.
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
mikemcgarry GMATNinja GMATNinjaTwo

Hi, I was wondering could one of you guys please explain why option E is incorrect? Our conclusion is "particularly loud clicks might be used by the dolphins to stun their prey at close range through sensory overload". E gives us an another reasoning which tells us that loud clicks may not be used to stun their prey at a close range but rather it is used to reveal a prey's presence. Please help me out and tell me where my reasoning is incorrect? Would greatly appreciate it!
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
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csaluja wrote:
mikemcgarry GMATNinja GMATNinjaTwo

Hi, I was wondering could one of you guys please explain why option E is incorrect? Our conclusion is "particularly loud clicks might be used by the dolphins to stun their prey at close range through sensory overload". E gives us an another reasoning which tells us that loud clicks may not be used to stun their prey at a close range but rather it is used to reveal a prey's presence. Please help me out and tell me where my reasoning is incorrect? Would greatly appreciate it!

Quote:
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 overload. Other toothed whales
can produce high pitched clicks. When these clicks hit an object, some of the sound will echo back to the 'sender'. By listening to the echo and interpreting the time it took before the echo came back, the dolphin estimate the distance of the object.

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 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.

csaluja, choice (E) is tempting because, as you said, it gives an alternative explanation for the loud clicks.

However, keep in mind that the speculation/conclusion is NOT that the loud clicks are only used to stun prey at close range. Rather, the speculation is that the clicking sounds "might have a second function." So it's perfectly fine if loud clicks have TWO functions: 1) to locate distant prey (as described by choice E) and 2) to stun prey at close range.

If we were told that the loud clicks were ONLY used to locate distant prey, then the speculation would be contradicted. But, as is, choice (E) does not necessarily interfere with the speculation.

Choice (B) is a much better answer.
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
GMATNinja wrote:
csaluja wrote:
mikemcgarry GMATNinja GMATNinjaTwo

Hi, I was wondering could one of you guys please explain why option E is incorrect? Our conclusion is "particularly loud clicks might be used by the dolphins to stun their prey at close range through sensory overload". E gives us an another reasoning which tells us that loud clicks may not be used to stun their prey at a close range but rather it is used to reveal a prey's presence. Please help me out and tell me where my reasoning is incorrect? Would greatly appreciate it!

Quote:
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 overload. Other toothed whales
can produce high pitched clicks. When these clicks hit an object, some of the sound will echo back to the 'sender'. By listening to the echo and interpreting the time it took before the echo came back, the dolphin estimate the distance of the object.

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 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.

csaluja, choice (E) is tempting because, as you said, it gives an alternative explanation for the loud clicks.

However, keep in mind that the speculation/conclusion is NOT that the loud clicks are only used to stun prey at close range. Rather, the speculation is that the clicking sounds "might have a second function." So it's perfectly fine if loud clicks have TWO functions: 1) to locate distant prey (as described by choice E) and 2) to stun prey at close range.

If we were told that the loud clicks were ONLY used to locate distant prey, then the speculation would be contradicted. But, as is, choice (E) does not necessarily interfere with the speculation.

Choice (B) is a much better answer.


Basically do you mean to say that clicking sounds being of a type that the prey is incapable of perceiving, regardless of volume ( in Option B) is equivalent to stunning the prey ( in premise). Effectively it means both mean only one function rather than 2 functions.
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
Situation: It says that dolphins emit clicking sounds and listen for echoes returning from distant objects in the water. Based on this information, marine biologists have speculated that those clicks might be used by dolphins to stun their prey.
Weaken: All we have to do is to prove dolphins use the clicking sound NOT to stun their prey. They use the click only to measure the distance, or the prey can’t perceive the click.


(A) Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.
This answer choice simply repeats the information given in the argument.

(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.
The click can’t be heard by dolphin’s prey, so it can be inferred that the prey won’t be stunned by the click.

(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.
We are not talking about the effectiveness of the clicking noise to its audience.

(D) Echolocation appears to give dolphins information about the richness of a source of food as well as about its direction.
This is an subjective response.

(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.
Still, we are not discussing about the volume of clicks. The arguments wants us to evaluate whether the click stun the prey or not!
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
GMATNinja
Can you explain why A is wrong?
I was stuck between A and B. I chose A.
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Some species of dolphins find their prey by echolocation; they emit [#permalink]
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akanshaxo wrote:
Can you explain why A is wrong?
I was stuck between A and B. I chose A.

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

(A) is a tempting trap, because when we read it we see a pattern, and may extend that pattern in a way that does not make complete sense.

In other words, from (A), we see that the dolphins use echolocation to locate distant prey, and that they continue to use it as they get closer to prey, and therefore, we may be tempted to decide that, even when they are at close range, they use the clicks for echolocation rather than for stunning prey.

This thinking is not supported, however.

Notice that choice (A) says nothing about what goes on when the dolphins are actually close to the prey. It says that they emit frequent clicks AT INTERMEDIATE DISTANCES as they CLOSE IN on the prey.

Yes, from what (A) says, we can tell that it is possible that dolphins use clicks for echolocation at close range, since they use clicks for echolocation at both long range an intermediate range. Even so, they may not use clicks for echolocation at close range, and further, even if they do use clicks for echolocation at close range, they may use them also to stun prey.

So, (A) does not clearly indicate anything about what goes on at close range, as opposed to a long or intermediate range, and does not say anything contrary to the speculation that, when close to prey, dolphins use loud clicks to stun the prey.
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
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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 overload.

Which of the following, if discovered to be true, would cast the most serious doubt on the correctness of the speculation described above?
Please find the explanation inline with the choices below:

(A) Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.
(Out of context, this is not discussed in the paragraph. Hence, should not be mentioned.)
(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.
(This is the correct option, since it explains when will the echolocation phenomenon will be adapted by the 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.
(This is the tricky choice that students will mark as their option, however it is out of context of the question asked.)
(D) Echolocation appears to give dolphins information about the richness of a source of food as well as about its direction.
(no info has been stated in the para about the richness of the 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.
(no proportionality has been stated in the para. Hence, irrelevant choice. )

Kindly give kudos if you liked the explanation! :)
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
VeritasKarishma Can you please comprehend the last line"Marine biologists .............through sensory overload"..
Thank you :-)
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
shuklaji wrote:
VeritasKarishma Can you please comprehend the last line"Marine biologists .............through sensory overload"..
Thank you :-)



Marine biologists have speculated-- speculated what?
that
those same clicking sounds --those sounds
might have a second function: have another function ,what function?
particularly loud clicks -- those loud clicks ,,which loud clicks (find their prey by echolocation)
might be used -ok
by the dolphins - ok
to stun their prey - i see, to stun
at close range--only at close range?
through sensory overload.--through their sensory overload (overload--means passing signals intensity in excess)

biologists think these clicking sounds can also be used to stun their prey at close run by overloading sensory signals( sending signal intensity high)

what's question? == >Weaken this thought.

What B says:
(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.

echolocation is useful if prey can not perceive it how much ever the high intensity is . So it means if dolphins want to stun their prey they can not use these echolocation signals . so biologists claim can not be correct.
how much is the volume is irrespective
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Some species of dolphins find their prey by echolocation; they emit [#permalink]
VeritasKarishma
Please give your analysis of correct option B
I chose Option E but GmatNinja clarified that doubt above
Why E wrong

Is B correct becoz prey won't be able to listen echo and in conclusion told by goving high clicks dolphin will stun prey by sensory overload so sensory overload means attavking to senses
I'm confused please clarify

Posted from my mobile device
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
saby1410 wrote:
VeritasKarishma
Please give your analysis of correct option B
I chose Option E but GmatNinja clarified that doubt above
Why E wrong

Is B correct becoz prey won't be able to listen echo and in conclusion told by goving high clicks dolphin will stun prey by sensory overload so sensory overload means attavking to senses
I'm confused please clarify

Posted from my mobile device


My 2 cents here:

Argument says: Dolphins find their prey by echolocation
COnclusion : These echos could stun their prey at close range

How to weaken?
echos don't tend to stun their prey

B says: due to this stun, prey may go away. So these echos stunning their prey doesn't make sense.
It means : You use something to catch . But if using this somethign can alert prey in advance then what's the use of even detecting?
Imagine: you want to kill mosquito, then you silent approach it . But if mosquito can easily stun your approach then your action of approaching become useless.

This is how I selected B:)

Hope it helps:)
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
Which of the following, if discovered to be true, would cast the most serious doubt on the correctness of the speculation described above?

We need an answer choice that would weaken the idea that 'those same clicking sounds might have a section function: particularly loud clicks might be used by the dolphins to stun their pray at close range through sensory overload.' Let's go through the choices.

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

We know that some species of dolphins find their prey by echolocation, emitting clicking sounds and listening for echoes from distant objects. Now, we're told they emit additional clicks at closer distances. Doesn't weaken the second function. A is out.

(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.

This choice tells us that echolocation only works IF the prey can't hear these clicks. If this was the case, then prey wouldn't be stunned by loud clicks. Keep this one.

(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.

We aren't discussing the effectiveness of the dolphin's stun -- we want to weaken the argument that dolphins emit loud clicks in order to stun their pray. C is gone.

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

Extra information. Out.

(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.

This choice doesn't really weaken the speculation of a second function. Dolphins use echolocation. The more distance a dolphin's prey, the louder these clicks must be. The suggestion of the second function is still intact here.

B is the best choice.
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Re: Some species of dolphins find their prey by echolocation; they emit [#permalink]
What does " regardless of VOLUME " mean in option B ? I crossed out the option bcs of this only. It's not VOLUME we are talking about rather we are talking about strength of sound. Expert please explain.

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