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Manatees, aquatic mammals inhabiting Florida’s rivers and coastal

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

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New post Updated on: 14 Jul 2018, 01:10
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A
B
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D
E

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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.

(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?

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Originally posted by ykaiim on 19 Jun 2010, 09:25.
Last edited by hazelnut on 14 Jul 2018, 01:10, edited 3 times in total.
Added OA.
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 22 Nov 2010, 13:05
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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 coastal  [#permalink]

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New post 20 Jun 2010, 11:10
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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 coastal  [#permalink]

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New post 20 Jun 2010, 07:43
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IMO B
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 20 Jun 2010, 11:26
IMO B.
water hyacinth beds can be disturbed or damaged by fast-moving boat
traffic. when Boats maintain low speeds, it cant worsen things.

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

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New post 20 Jun 2010, 22:00
Yes B.

Apply negation on B. And arg will reverse.
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 20 Jun 2010, 23:36
E...if they cannot distinguish different boat sounds, there won't be much difference (the situation will maybe improve), and the conclusion is weakened...
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 21 Jun 2010, 00:43
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Now I am hesitant on B. But the only contenders are B / E.

E is only one which DELINKS the speed of boat as the key force of the argument.
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 21 Jun 2010, 01:50
E IMO We are supposed to logically negate the argument. E does that by making the stituation from worse ------ > Same .

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

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New post 21 Jun 2010, 09:11
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I believe the answer should be E. B though mentions that fast boats can kill the manatees, but no where it mentions if the slow boats are going to help and reduce the collisions.

B answer choice is like a Shell game.

OA please. Thank You.

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

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New post 21 Jun 2010, 10:13
What is a shell game? How is it affecting the argument?

amp0201 wrote:
I believe the answer should be E. B though mentions that fast boats can kill the manatees, but no where it mentions if the slow boats are going to help and reduce the collisions.

B answer choice is like a Shell game.

OA please. Thank You.

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

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New post 21 Jun 2010, 14:02
Shell game is like the answer choice most similar to correct one, though not the correct one.

The argument's conclusion is - slower boats might worsen the problem.

Answer choice E says Manatees are not able to hear noises at any levels. Hence the problem won't worsen but will stay same.

Answer choice B is about faster boats and nothing to say about slower boats.

Hence I believe to be E rather than B. Thank You.

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

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New post 22 Jun 2010, 21:17
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.



what's the background sound means here; They'll not be able to distinguish b/w Boat noise and normal noise?
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 26 Jul 2010, 02:37
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E.
Seemed easy to me.

because boats drive fast they kill manatee.
Why? there are two reasons: either manatees are sluggish or deaf.
conclusion: author says that deafness kills M. we must introduce evidence that would make author to reconsider his her conclusion by saying "ohh... I am stupid I did not account for this"

E says that M can't discern sounds, so they die not due to deafness, but becuase they are sluggish.
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 26 Jul 2010, 04:26
thought D was the answer..
on reverification got E as correct
wasted approx 6 min :(
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 26 Jul 2010, 21:54
i also thought B :cry:
but E it shud be
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 21 Nov 2010, 04:12
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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.
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Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal  [#permalink]

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New post 07 Jan 2011, 06:42
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 coastal  [#permalink]

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New post 27 Nov 2013, 03:39
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 coastal  [#permalink]

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New post 28 Nov 2013, 21:23
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?
Re: Manatees, aquatic mammals inhabiting Florida’s rivers and coastal &nbs [#permalink] 28 Nov 2013, 21:23

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