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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Elite official CR Revision Question # 5
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richachampion
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richachampion
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OA: E
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Brent@GMATPrepNow
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Argument summary:richachampion 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.
Premise: Manatees swim close to the surface and are frequently killed in collisions with boats.
Premise: To address the problem, boats should travel at very low speeds.
Premise: Manatees can't hear low-pitched sounds and a boat's sound lowers in pitch as the boat slows.
Conclusion: Reducing boat speeds may make things worse.
Question stem: Which of the following, if true, casts most doubt on the conclusion?
A. has no effect on the conclusion
B. unrelated to conclusion about whether slow boats will make things worse
C. doesn't effect the conclusion about whether slow boats will make things worse
D. doesn't effect the conclusion about whether slow boats will make things worse
E. NICE. The idea behind the author's conclusion is that manatees may be able to at least HEAR fast-moving boats approaching and get out of the way. So, if slow-moving boats are very silent, the manatees will not hear them and will get hit. Answer choice E says that manatees don't hear fast-moving boats and they don't hear slow-moving boats. That significantly weakens the author's conclusion.
Answer: E
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Brent
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richachampion
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sir, this is my take =Brent@GMATPrepNow wrote:Answer choice E says that manatees don't hear fast-moving boats and they don't hear slow-moving boats. That significantly weakens the author's conclusion.
Answer: E
Cheers,
Brent
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.
To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. :This solution was predicted assuming that it is the high-speed collisions that cause the death of Manatees.
however, the logic where the above is contradicted is quite inappropriate.
Unfortunately, manatees are unable to hear low-pitched sounds and a boat's sound lowers in pitch as the boat slows. →
They are trying to conclude that the cause of the deaths is collisions: high-speed or low-speed collisions and the chances of collision will increase with the slow speed as M's will not be able to hear the boat sound. This is quite different than what has established above: High-speed collisions are responsible for deaths.
so, our job is to find an option that says the sound of the boat has no proportionality to the deaths of M's.
Right Sir?
Last edited by richachampion on Sat Aug 05, 2017 2:03 am, edited 1 time in total.
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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.
are frequently killed in collisions with boats. → How can the collisions be stopped or minimized?
To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. : This solution was predicted assuming that it is the high-speed collisions that cause the death of Manatees.
Then suddenly a new argument is introduced to contradict the solution →
Unfortunately, manatees are unable to hear low-pitched sounds and a boat's sound lowers in pitch as the boat slows.
But the truth is that this argument has no connection with the argument and solution established above: speed and collision and death.
are frequently killed in collisions with boats. → How can the collisions be stopped or minimized?
To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. : This solution was predicted assuming that it is the high-speed collisions that cause the death of Manatees.
Then suddenly a new argument is introduced to contradict the solution →
Unfortunately, manatees are unable to hear low-pitched sounds and a boat's sound lowers in pitch as the boat slows.
But the truth is that this argument has no connection with the argument and solution established above: speed and collision and death.
R I C H A,
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DavidG@VeritasPrep
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It might be helpful to consider a simpler version of the logic.richachampion 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.
are frequently killed in collisions with boats. → How can the collisions be stopped or minimized?
To address the problem, boat traffic in manatee-populated waters is being required to maintain very low speeds. : This solution was predicted assuming that it is the high-speed collisions that cause the death of Manatees.
Then suddenly a new argument is introduced to contradict the solution →
Unfortunately, manatees are unable to hear low-pitched sounds and a boat's sound lowers in pitch as the boat slows.
But the truth is that this argument has no connection with the argument and solution established above: speed and collision and death.
Imagine there's an epidemic in a particular neighborhood of small children getting hit by cars. The proposed solution: lower the speed limit. Now someone in the neighborhood insists that this solution will make the problem worse, as slower cars make less noise and so the kids won't hear the cars coming.
If it turned out that all the kids playing in the street had earbuds in and so couldn't hear the cars even when they were driving fast, then we know that the speed limit won't make things worse. The kids never heard the cars in the first place, and so the fact that there are quieter cars doesn't present a new problem.
