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Manatees, aquatic mammals inhabiting Florida s rivers and

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Re: Manatees, aquatic mammals [#permalink]

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New post 22 Nov 2010, 12:05
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raghavs wrote:
Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to
the surface and are frequently killed in collisions with boats. To address the problem,
boat traffic in manatee-populated waters is being required to maintain very low speeds.
Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers
in pitch as the boat slows. Therefore, this approach may in fact make things worse rather
than better.
Which of the following, if true, casts most doubt on the conclusion?
A. The areas where boats would have to maintain low speeds were decided partly on
the basis of manatee-population estimates and partly from numbers of reported
collisions between manatees and boats.
B. Because the water hyacinth that manatees feed on grows best in water that is
nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic.
C. Over the last several decades, boat traffic in Florida’s coastal waters has been
increasing almost continuously and now represents the greatest threat to the
endangered manatee population.
D. The sound of a boat engine generally travels much further under water than it
does through the air.

E. When experimenters exposed manatees to the recorded sounds of boats moving at
various speeds, the creatures were unable to discern the sounds over normal
background noise.


Premises:
- To avoid manatee-boat collisions, boat traffic in manatee-populated waters is being required to maintain very low speeds.
- Manatees are unable to hear low-pitched sounds.
- A boat’s sound lowers in pitch as the boat slows.

Conclusion:
This approach (the approach is 'reducing boat speeds') may make things worse.

If we have to cast doubt on the conclusion, we have to show that reducing boat speeds may not make things worse.
Option (A): It doesn't matter how the areas were decided. This option doesn't say that reducing boat speed will not increase collisions.
Option (B): Out of scope of our question. We need to focus on boat-manatee collisions.
Option (C): Boat traffic is increasing. But it doesn't say how reducing speed may not increase number of collisions.
Option (D): It does have something to do with speed of sound. But it says that sound of a boat travels much further under water than through air. If sounds are low pitched manatees may not be able to hear them, irrespective of how far the sounds travel and how far the manatees are from the boat. Lowering of speed of boats could make the situation worse and hence, it doesn't weaken my conclusion.
Option (E): Manatees are unable to discern sounds of boat moving at different speeds over background noise. This means, it doesn't matter at what speed the boat is moving. The manatee will not be able to discern its sound (whether high pitched or low pitched). Hence, reducing the speeds of the boats will not have a negative impact on the number of collisions. It might even have some positive effect since the slow moving boat may be able to see the manatee and change its course in time. Hence, this option weakened our conclusion.
Answer (E).

Note: To weaken the conclusion, I only need to prove that the approach may not make things worse. I don't have to show that it necessarily improves matters.
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 07 Jan 2011, 05:42
B if something, strengthenes the argument saying that slow boats is a good plan.
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 27 Nov 2013, 02:39
krypt wrote:
I think the answer is E.

The hypothesis is that boats traveling slow = less manatees killed. However, manatees can't hear slow boats and therefore, slow boats will make the problem WORSE. The argument is saying that boats traveling at various speeds will kill less manatees than all boats traveling slowly on the account that manatees can't hear slow boats.

To cast doubt on this, we can show that manatees can't hear various speeds. Thus, mandating slow boats will not make the problem WORSE, it should stay the same.


Great explanation! very helpful
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 28 Nov 2013, 20:23
Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats. To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows. Therefore, this approach may in fact make things worse rather than better.

Which of the following, if true, casts most doubt on the conclusion?

A. The areas where boats would have to maintain low speeds were decided partly on
the basis of manatee-population estimates and partly from numbers of reported
collisions between manatees and boats.
B. Because the water hyacinth that manatees feed on grows best in water that is
nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic.
C. Over the last several decades, boat traffic in Florida’s coastal waters has been
increasing almost continuously and now represents the greatest threat to the
endangered manatee population.
D. The sound of a boat engine generally travels much further under water than it
does through the air.
E. When experimenters exposed manatees to the recorded sounds of boats moving at
various speeds, the creatures were unable to discern the sounds over normal
background noise.

I marked the OA by PoE, but I was not much clear on the argument. Can someone explain on the argument and answer choice?

Can someone please explain this. I still dont understand why E is correct.

Premise: Manatees swim near the surface and get killed. To solve this problem, even low speed boats are not of much use because the Manatees cannot hear the low pitch sound of the boats.
Conclusion: The above approach may actually result in more Manatees getting killed.

To weaken the conclusion, we have to find an option where more Manatees are NOT getting killed, right?

Option E states that Manatees cannot distinguish low pitch sounds, so this will actually result in more Manatees getting killed. This seems to strengthen the conclusion. Can the experts help me on this?

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 29 Nov 2013, 03:07
Agree. E is the answer.

D is a trap answer.

The sound of a boat engine generally travels much further under water than it
does through the air.


It says that sound travels much further under water than it does through air. The choice is more generic and does not say anything about the manatees' hearing capacity.
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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Conclusion: Therefore, this approach may in fact make things worse rather than better.

Reasoning: High boat speeds kills manatees. Slow boat speeds kills more manatees because manatees cannot hear any sound. To weaken the argument, the statement must provide that slow boat speeds do not kill any more than high boat speeds. (Wrong answers are neutral or provide reasons why slow boat speeds do kill more manatees than high boat speeds.)

A. The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported
collisions between manatees and boats. Neutral. Statement does not cast doubt.

B. Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic.Wrong. Statement provides a reason why more manatees are present in waters with slow boat speeds.

C. Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the
endangered manatee population. Neutral. More boats kill more manatees; nothing about boat speeds.

D. The sound of a boat engine generally travels much further under water than it does through the air. Opposite answer - admittedly, this one threw me off. I forgot if this question were a strengthen or weaken, and key words such as "engine" + "travel much further" made a good trap. Brain fail.

E. When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal
background noise. OK - that slow boat speeds do not kill any more than high boat speeds.

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 07 Feb 2014, 06:22
+1 E

The conclusion here is that slow boats emit lower pitch sounds and since manatee are unable to hear low pitch sounds, the situation can become worst with slow boats. The hearing ability of manatees is what the conclusion depends on, and must be targeted.

E clearly shows that sound hardly plays any role in alertness of manatee. hence it weakens the conclusion.

D is tempting, but it fails to explain why manatees collide with faster moving boats. faster boats emit higher pitch sounds and should in fact alert the manatees.
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 07 Feb 2014, 07:06
mejia401 wrote:
Conclusion: Therefore, this approach may in fact make things worse rather than better.

Reasoning: High boat speeds kills manatees. Slow boat speeds kills more manatees because manatees cannot hear any sound. To weaken the argument, the statement must provide that slow boat speeds do not kill any more than high boat speeds. (Wrong answers are neutral or provide reasons why slow boat speeds do kill more manatees than high boat speeds.)

A. The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported
collisions between manatees and boats. Neutral. Statement does not cast doubt.

B. Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic.Wrong. Statement provides a reason why more manatees are present in waters with slow boat speeds.

C. Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the
endangered manatee population. Neutral. More boats kill more manatees; nothing about boat speeds.

D. The sound of a boat engine generally travels much further under water than it does through the air. Opposite answer - admittedly, this one threw me off. I forgot if this question were a strengthen or weaken, and key words such as "engine" + "travel much further" made a good trap. Brain fail.

E. When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal
background noise. OK - that slow boat speeds do not kill any more than high boat speeds.



So you are saying that sound is the only thing that can kill manatees. If I am hit by a ball at 5 mph it might sting a little but if I am hit by the same ball at 50 mpg I might die. Basic physics 101
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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Manatees, aquatic mammals inhabiting Florida’s rivers and coastal wate [#permalink]

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Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats. To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows. Therefore, this approach may in fact make things worse rather than better.

Which of the following, if true, casts most doubt on the conclusion?

A. The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported
collisions between manatees and boats.
B. Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic.
C. Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the
endangered manatee population.
D. The sound of a boat engine generally travels much further under water than it does through the air.
E. When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal
background noise.

Posted here, because the OA is not provided in other topics.

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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal wate [#permalink]

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TooLong150 wrote:
Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats. To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows. Therefore, this approach may in fact make things worse rather than better.

Which of the following, if true, casts most doubt on the conclusion?


Premise 1: aquatic mammals are frequently killed in collisions with boats.
Premise 2: manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows.
Conclusion: slowing the boat may in fact make things worse rather than better..........If the boat is slow, Manatees will not be able to hear the sound and will have more collsions.


A. The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported
collisions between manatees and boats.
Incorrect: Our of scope.It doesn't matter how the speed of boat is defined.
B. Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic.
Incorrect: Our of scope.It doesn't matter how the speed of boat is defined.
C. Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the
endangered manatee population.
Incorrect:Although it is very tempting but the argument says frequently killed in collisions with boat ,To address the problem.So, we are only considered with mammals killed directly by collision.
D. The sound of a boat engine generally travels much further under water than it does through the air.
Incorrect: Our of scope.It doesn't matter how much farther the sound travels in two mediums.
E. When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal
background noise.
Correct: If manatees are not able to differentiate between the sound of high speed and the sound of low speed boat then slowing is NOT worsening the situation

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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal wate [#permalink]

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New post 15 May 2015, 06:06
TooLong150 wrote:
Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats. To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows. Therefore, this approach may in fact make things worse rather than better.

Which of the following, if true, casts most doubt on the conclusion?

A. The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported
collisions between manatees and boats.
B. Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic.
C. Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the
endangered manatee population.
D. The sound of a boat engine generally travels much further under water than it does through the air.
E. When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal
background noise.



Posted here, because the OA is not provided in other topics.

ITS E.E says that creatures are not able to distinguish between high n low pitch sounds.So,situation cannot be worse.

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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Hello from the GMAT Club VerbalBot!

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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal wate [#permalink]

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New post 29 Jul 2016, 20:44
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My 2 cents:

P1: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal waters, swim close to the surface and are frequently killed in collisions with boats.
P2: To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds.
P3: Unfortunately, manatees are unable to hear low-pitched sounds and a boat’s sound lowers in pitch as the boat slows.

Conc: Therefore, this approach may in fact make things worse rather than better.

Problem#1 is HS. The solution to this problem creates another problem that is LS, Pob#2.
Few assumptions: Author assumes that fish can hear the sound and can make out the difference between HPS and LPS.
Lets look out for options that talk about M and sound of boats or can prove that advantages of lowering the speed boat for M would outweighs those of high speed boats.

Which of the following, if true, casts most doubt on the conclusion?

A. The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported collisions between manatees and boats.
>> Problem talks abt M and their ability to hear sound. Doesn't give much info. to evaluate the conc. Ignore.
B. Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat traffic.
>> This presents another disadvantage or HS apart from collision. So lowering the speed will have other advantages as well. But does it effect our conc. Can/Can't. Hence lets visit other options.
C. Over the last several decades, boat traffic in Florida’s coastal waters has been increasing almost continuously and now represents the greatest threat to the endangered manatee population.
>> Introducing another problem apart from what mentioned in premise. Ignore.
D. The sound of a boat engine generally travels much further under water than it does through the air.
>> it doesn't help much. Also M travel close to surface. ignore.
E. When experimenters exposed manatees to the recorded sounds of boats moving at various speeds, the creatures were unable to discern the sounds over normal background noise.
>> This mentions about M ability to distinguish between sounds of boat moving at various speed and background noise. Note this option talks in general abt M's ability to discern sound. Bingo!
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 15 Sep 2016, 09:02
krypt wrote:
I think the answer is E.

The hypothesis is that boats traveling slow = less manatees killed. However, manatees can't hear slow boats and therefore, slow boats will make the problem WORSE. The argument is saying that boats traveling at various speeds will kill less manatees than all boats traveling slowly on the account that manatees can't hear slow boats.

To cast doubt on this, we can show that manatees can't hear various speeds. Thus, mandating slow boats will not make the problem WORSE, it should stay the same.



Even I am thinking on the same lines. The idea here is weather the new rule will make the situation worse or not. Nothing is mentioned about saving or reducing the number of accidents.

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 04 May 2017, 11:49
The hypothesis is that boats traveling slow = less manatees killed. However, manatees can't hear slow boats and therefore, slow boats will make the problem WORSE. The argument is saying that boats traveling at various speeds will kill less manatees than all boats traveling slowly on the account that manatees can't hear slow boats.

To cast doubt on this, we can show that manatees can't hear various speeds. Thus, mandating slow boats will not make the problem WORSE, it should stay the same.


E says that the manatees were unable to hear the boat noises at any speed that was tested ("various speeds"). In other words, they are already deaf to the boat sounds, so there is no way that things could get worse at lower speeds.

A. The areas where boats would have to maintain low speeds were decided partly on the basis of manatee-population estimates and partly from numbers of reported collisions between manatees and boats. --> This info does not help as it provides information about the environment and nothing else.

B. Because the water hyacinth that manatees feed on grows best in water that is nearly still, water hyacinth beds can be disturbed or damaged by fast-moving boat traffic. --> Water hyacinths do not feature in the argument. So No.

C. Over the last several decades, boat traffic in Florida's coastal waters has been increasing almost continuously and now represents the greatest threat to the endangered manatee population. --> Ok, so the boat population is increasing and is a threat (in spite of the technicalities et al). For keeps.

D. The sound of a boat engine generally travels much further under water than it does through the air. --> But no mention in the premises about the Manatees hearing through air. This comparison does not weaken the logic of the argument in any way. It is not about the speed of sound rather it is about the pitch.

E. When experimenters exposed manatees to the recorded sounds of boats moving at
various speeds, the creatures were unable to discern the sounds over normal
background noise --> So Manatees can actually discern (perceive the change in) sounds and this weakens the argument because it clearly contradicts Unfortunately, manatees are unable to hear low-pitched sounds and a boat's sound lowers in pitch as the boat slows.

E is the best choice here.
_________________

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Anaira Mitch

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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New post 08 Jul 2017, 03:40
E.
E attacks the conclusion by attacking the method of reasoning. He states that Manes can not hear the sounds of the slow boats . Hence, slow boats make the problem worse. But What if they can not hear any sound at all. Then falsifying the reasoning itself. Stating that It is not the slow boats that make the problem worse but the boats itself and worsening doesn't depend on the speed of the boat.

Hence, My go is with E.

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Re: Manatees, aquatic mammals inhabiting Florida s rivers and   [#permalink] 08 Jul 2017, 03:40

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