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# Manatees, aquatic mammals inhabiting Florida s rivers and

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

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27 Nov 2013, 02:39
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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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.

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

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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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29 Nov 2013, 03:07

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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06 Feb 2014, 18:26
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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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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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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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31 May 2014, 16:34
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Re: Manatees, aquatic mammals inhabiting Florida s rivers and [#permalink]

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06 Jun 2015, 09:56
Hello from the GMAT Club VerbalBot!

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

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03 Jul 2016, 15:25
Hello from the GMAT Club VerbalBot!

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

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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.
Re: Manatees, aquatic mammals inhabiting Florida s rivers and   [#permalink] 15 Sep 2016, 09:02

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