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Harbor Porpoises---Assumption

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Harbor Porpoises---Assumption

by amysky_0205 » Sun Mar 10, 2013 6:13 pm
To prevent harbor porpoises from getting tangled in its nets and suffocating, a fishing company installed acoustic alarms on all its boats that fish in waters off Massachusetts. The sound emitted temporarily disorients the porpoises and frightens them away. Since the installation of the alarms, the average number of porpoises caught in the company's nets has dropped from eight to one per month. The alarms, therefore, are saving the lives of harbor porpoises in those waters.

Which of the following is an assumption on which the argument depends?

A. The use of acoustic alarms increases the number of commercial fish caught by the fishing company's boats.

B. When disoriented, harbor porpoises are not significantly more likely to be killed by other boats.

C. Environmentalists advocate the use of acoustic alarms as a means of protecting the harbor porpoise population.

D. The alarms were installed at the time of year when harbor porpoises are most plentiful in the Massachusetts waters.

E. The cost of installing acoustic alarms on fishing boats is less than the cost of repairing nets damaged by harbor porpoises.

OA: B

can someone explain this one?

I chose D instead of the right answer.

thank you so much!
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by srcc25anu » Sun Mar 10, 2013 8:47 pm
If we negate B the conclusion falls apart that alarms are not saving the lives of porpoises. If when disoriented, the porpoises were killed in large by other boats, the conclusion would not hold water. Hence it is an assumption that the porpoises saved one way (by alarms) is not killed in large numbers by any other way. Hence B is correct assumption.
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by Deepthi Subbu » Tue Mar 12, 2013 1:10 am
I am not quite convinced with the OA .The statement is talking about saving porpoises that could not get entangled in the net and not those that encounter a natural death. B talks about the latter.

Though I am not very convinced with D, it still picked it considering the point I put forth.

Whats the source of this question?
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by himu » Tue Mar 12, 2013 2:24 am
amysky_0205 whats the source of this Q ?

Also, +1 for B.

@Deepthi Subbu as @srcc25anu correctly pointed negating B makes the conclusion fall apart.

Premise 1 :
To prevent harbor porpoises from getting tangled in its nets and suffocating, a fishing company installed acoustic alarms on all its boats that fish in waters off Massachusetts.
Premise 2 : The sound emitted temporarily disorients the porpoises and frightens them away
Premise 3: porpoises caught in the company's nets has dropped from eight to one per month

Conclusion : alarms, therefore, are saving the lives of harbor porpoises in those waters.


NOw, consider that due to alarms, the porpoises frightened & them away & when they are moving away they are significantly more likely to be killed by other boats.
THEN THE CONCLUSION : ---> alarms, therefore, are saving the lives of harbor porpoises in those waters *COMPLETELY* falls apart !

Hope this help,
Cheers,
~Himu.
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by Ankur87 » Wed Mar 13, 2013 8:27 am
Deepthi Subbu wrote:I am not quite convinced with the OA .The statement is talking about saving porpoises that could not get entangled in the net and not those that encounter a natural death. B talks about the latter.

Though I am not very convinced with D, it still picked it considering the point I put forth.

Whats the source of this question?
B is the best answer out of all 5 options.


The fishing company wants to prevent harbor porpoises. They don't want harbor porpoises to be killed (like it is mentioned that "saving the lives of harbor porpoises").

If we negate B :
When disoriented, harbor porpoises are significantly more likely to be killed by other boats.

Then the argument will fall apart.

So this is the correct answer.
Hope this explanation helps.
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