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Feathers recently taken from seabirds stuffed and

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Feathers recently taken from seabirds stuffed and  [#permalink]

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New post Updated on: 18 Sep 2017, 20:18
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Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species. Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird, these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.

The argument depends on assuming that

(A) the proportion of a seabird’s diet consisting of fish was not as high, on average, in the 1880s as it is today

(B) the amount of mercury in a saltwater fish depends on the amount of pollution in the ocean habitat of the fish

(C) mercury derived from fish is essential for the normal growth of a seabird’s feathers

(D) the stuffed seabirds whose feathers were tested for mercury were not fully grown

(E) the process used to preserve birds in the 1880s did not substantially decrease the amount of mercury in the birds’ feathers

Source: LSAT

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Originally posted by creativeminddu on 19 Nov 2013, 03:11.
Last edited by broall on 18 Sep 2017, 20:18, edited 1 time in total.
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 19 Nov 2013, 20:18
5
Veritas teaches a technique called the "assumption negation technique" that is very effective for solving critical reasoning assumption questions. In order to utilize the assumption negation technique, narrow down your list of potential answers to a couple you feel may be correct. Then, for each answer choice, negate the choice, insert the negated statement back into the argument, and gauge whether or not the argument falls apart. A correct assumption, when negated, will destroy the argument.

This argument is stating that mercury levels are higher in saltwater fish now than in the 1880s, and it uses the comparison of the mercury in feathers of currently living birds vs. those of birds stuffed in the 1880s.

Negating answer choice E, we have: "the process used to preserve birds in the 1880s DID substantially decrease the amount of mercury in the birds’ feathers." If that is the case, then the comparison between living birds and those stuffed in the 1880s is no longer relevant, as the mercury in those birds' feathers was significantly altered. This destroys the link between premises and conclusion, and thus answer choice E is a required assumption.

I hope this helps!!!
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 05 Oct 2017, 03:38
VeritasPrepBrandon wrote:
Veritas teaches a technique called the "assumption negation technique" that is very effective for solving critical reasoning assumption questions. In order to utilize the assumption negation technique, narrow down your list of potential answers to a couple you feel may be correct. Then, for each answer choice, negate the choice, insert the negated statement back into the argument, and gauge whether or not the argument falls apart. A correct assumption, when negated, will destroy the argument.

This argument is stating that mercury levels are higher in saltwater fish now than in the 1880s, and it uses the comparison of the mercury in feathers of currently living birds vs. those of birds stuffed in the 1880s.

Negating answer choice E, we have: "the process used to preserve birds in the 1880s DID substantially decrease the amount of mercury in the birds’ feathers." If that is the case, then the comparison between living birds and those stuffed in the 1880s is no longer relevant, as the mercury in those birds' feathers was significantly altered. This destroys the link between premises and conclusion, and thus answer choice E is a required assumption.

I hope this helps!!!


hi

its fairly easy problem, and like everyone, I also got it right, but...
I was wondering if you could tell me whether the way I have eliminated "C" is okay

Assumption is an unstated premise, but the premise that "C" states is clearly stated in the argument, so it cannot be an unstated premise, so I have ruled it out. Is that okay ..?

thanks in advance, man
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 25 Dec 2017, 12:10
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creativeminddu wrote:
Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species. Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird, these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.

The argument depends on assuming that

(A) the proportion of a seabird’s diet consisting of fish was not as high, on average, in the 1880s as it is today

(B) the amount of mercury in a saltwater fish depends on the amount of pollution in the ocean habitat of the fish

(C) mercury derived from fish is essential for the normal growth of a seabird’s feathers

(D) the stuffed seabirds whose feathers were tested for mercury were not fully grown

(E) the process used to preserve birds in the 1880s did not substantially decrease the amount of mercury in the birds’ feathers

Source: LSAT


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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 25 Dec 2017, 15:50
Went with E


(E) the process used to preserve birds in the 1880s did not substantially decrease the amount of mercury in the birds’ feather.

The argument has to consider the answer E before making the statement "mercury levels in saltwater fish are higher now than they were 100 years ago"
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 08 May 2018, 07:59
gmatcracker2018 wrote:
VeritasPrepBrandon wrote:
Veritas teaches a technique called the "assumption negation technique" that is very effective for solving critical reasoning assumption questions. In order to utilize the assumption negation technique, narrow down your list of potential answers to a couple you feel may be correct. Then, for each answer choice, negate the choice, insert the negated statement back into the argument, and gauge whether or not the argument falls apart. A correct assumption, when negated, will destroy the argument.

This argument is stating that mercury levels are higher in saltwater fish now than in the 1880s, and it uses the comparison of the mercury in feathers of currently living birds vs. those of birds stuffed in the 1880s.

Negating answer choice E, we have: "the process used to preserve birds in the 1880s DID substantially decrease the amount of mercury in the birds’ feathers." If that is the case, then the comparison between living birds and those stuffed in the 1880s is no longer relevant, as the mercury in those birds' feathers was significantly altered. This destroys the link between premises and conclusion, and thus answer choice E is a required assumption.

I hope this helps!!!


hi

its fairly easy problem, and like everyone, I also got it right, but...
I was wondering if you could tell me whether the way I have eliminated "C" is okay

Assumption is an unstated premise, but the premise that "C" states is clearly stated in the argument, so it cannot be an unstated premise, so I have ruled it out. Is that okay ..?

thanks in advance, man


Hi gmatcracker2018,
I don't think C is stated in the argument.

(C) mercury derived from fish is essential for the normal growth of a seabird’s feathers - Incorrect

mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird -- We can't infer that mercury is essential for the normal growth based on this sentence.
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Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 30 Jun 2018, 22:18
GMATNinja nightblade354 VeritasPrepKarishma pikolo2510 generis

Can you help me to understand the argument?

Quote:
Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species.


Birds from today have 100 mg of mercury (for e.g) than those that lived in 1980 who had
50 mg of mercury. Both birds are of same species.

Quote:
Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird, these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.

Mercury found in birds' feathers is derived from fish that birds eat.
There is a direct linear relationship between accumulation of mercury in feathers and
amount of fish that birds eat.

Final conclusion:
mercury levels in saltwater fish are higher now than they were 100 years ago.

Here is where I faltered? What a scope shift from birds to fish in the argument? I am nowwhere given
a hint to relate mercury level in fish. It is the birds that eat fish, how do I know mercury levels in fish and to
what do I co-relate it to?
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Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 01 Jul 2018, 00:57
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adkikani wrote:
GMATNinja nightblade354 VeritasPrepKarishma pikolo2510 generis

Can you help me to understand the argument?

Quote:
Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species.


Birds from today have 100 mg of mercury (for e.g) than those that lived in 1980 who had
50 mg of mercury. Both birds are of same species.

Quote:
Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird, these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.

Mercury found in birds' feathers is derived from fish that birds eat.
There is a direct linear relationship between accumulation of mercury in feathers and
amount of fish that birds eat.

Final conclusion:
mercury levels in saltwater fish are higher now than they were 100 years ago.

Here is where I faltered? What a scope shift from birds to fish in the argument? I am nowwhere given
a hint to relate mercury level in fish. It is the birds that eat fish, how do I know mercury levels in fish and to
what do I co-relate it to?


Hi adkikani,

1. Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species.

2. Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird--> the fish is the source of Mercury in the seabird's feather

these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.---> Based on the premises 1 and 2 we can infer the given conclusion.


1.the proportion of a seabird’s diet consisting of fish was not significantly lower, on average, in the 1880s as it is today.
2. The seabirds whose feathers have been stuffed and preserved since the 1880s were not significantly younger than those whose feathers were taken recently.

Are these also valid assumptions?


AjiteshArun , GMATNinja , mikemcgarry , egmat , RonPurewal , DmitryFarber , MagooshExpert , ccooley , GMATNinjaTwo ,
VeritasPrepKarishma ,other experts-- please enlighten
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 01 Jul 2018, 11:20
adkikani wrote:
GMATNinja nightblade354 VeritasPrepKarishma pikolo2510 generis

Can you help me to understand the argument?

Quote:
Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species.


Birds from today have 100 mg of mercury (for e.g) than those that lived in 1980 who had
50 mg of mercury. Both birds are of same species.

Quote:
Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird, these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.

Mercury found in birds' feathers is derived from fish that birds eat.
There is a direct linear relationship between accumulation of mercury in feathers and
amount of fish that birds eat.

Final conclusion:
mercury levels in saltwater fish are higher now than they were 100 years ago.

Here is where I faltered? What a scope shift from birds to fish in the argument? I am nowwhere given
a hint to relate mercury level in fish. It is the birds that eat fish, how do I know mercury levels in fish and to
what do I co-relate it to?


the analysis of the argument was perfect :thumbup:

As you see there is a big scope shift. The assumption that should straight popup in your head is "Mercury in saltwater fish is directly responsible for the mercury in the bird's feather" . That's how you can draw the conclusion.

Hope this helps!
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Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 02 Jul 2018, 05:18
adkikani, the above explanations are good. As for me, I simply negated (E):

(E) the process used to preserve birds in the 1880s did substantially decrease the amount of mercury in the birds’ feathers

If this is the statement, then the argument completely falls apart, and hence is the answer. Negation is always great on assumptions questions!
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 07 Jul 2018, 11:45
Skywalker18 wrote:
adkikani wrote:
GMATNinja nightblade354 VeritasPrepKarishma pikolo2510 generis

Can you help me to understand the argument?

Quote:
Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species.


Birds from today have 100 mg of mercury (for e.g) than those that lived in 1980 who had
50 mg of mercury. Both birds are of same species.

Quote:
Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird, these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.

Mercury found in birds' feathers is derived from fish that birds eat.
There is a direct linear relationship between accumulation of mercury in feathers and
amount of fish that birds eat.

Final conclusion:
mercury levels in saltwater fish are higher now than they were 100 years ago.

Here is where I faltered? What a scope shift from birds to fish in the argument? I am nowwhere given
a hint to relate mercury level in fish. It is the birds that eat fish, how do I know mercury levels in fish and to
what do I co-relate it to?


Hi adkikani,

1. Feathers recently taken from seabirds stuffed and preserved in the 1880s have been found to contain only half as much mercury as feathers recently taken from living birds of the same species.

2. Since mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird--> the fish is the source of Mercury in the seabird's feather

these results indicate that mercury levels in saltwater fish are higher now than they were 100 years ago.---> Based on the premises 1 and 2 we can infer the given conclusion.


1.the proportion of a seabird’s diet consisting of fish was not significantly lower, on average, in the 1880s as it is today.
2. The seabirds whose feathers have been stuffed and preserved since the 1880s were not significantly younger than those whose feathers were taken recently.

Are these also valid assumptions?


AjiteshArun , GMATNinja , mikemcgarry , egmat , RonPurewal , DmitryFarber , MagooshExpert , ccooley , GMATNinjaTwo ,
VeritasPrepKarishma ,other experts-- please enlighten

Skywalker18, you nailed it!

We are specifically told that the "mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird." Although we aren't given the exact mercury levels in the fish, we can infer that, all else equal, increasing the amount of fish eaten would increase mercury levels in the feathers. Also, increasing the mercury levels in the fish would likely increase mercury levels in the feathers.

And, yes, your highlighted assumptions (variations of choice A and choice D) would be valid assumptions. If either of those highlighted assumptions were not true, the argument would fall apart. You deserve a cookie. :-)
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 09 Jul 2018, 23:48
GMATNinja wrote:

Skywalker18, you nailed it!

We are specifically told that the "mercury that accumulates in a seabird’s feathers as the feathers grow is derived from fish eaten by the bird." Although we aren't given the exact mercury levels in the fish, we can infer that, all else equal, increasing the amount of fish eaten would increase mercury levels in the feathers. Also, increasing the mercury levels in the fish would likely increase mercury levels in the feathers.

And, yes, your highlighted assumptions (variations of choice A and choice D) would be valid assumptions. If either of those highlighted assumptions were not true, the argument would fall apart. You deserve a cookie. :-)



Thank you GMATNinja sir for your kind words :-)
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Re: Feathers recently taken from seabirds stuffed and  [#permalink]

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New post 11 Jul 2018, 21:08
(E) the process used to preserve birds in the 1880s did not substantially decrease the amount of mercury in the birds’ feathers

Negate this option:-
The process used to preserve birds in the 1880s DID SUBSTANTIALLY decrease the amount of mercury in the birds’ feathers.
This will make the argument fall apart.
If the mercury levels were altered deliberately, the comparison between birds of 1880s and birds of today becomes absurd.

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Re: Feathers recently taken from seabirds stuffed and &nbs [#permalink] 11 Jul 2018, 21:08
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