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Samples from the floor of a rock shelter in Pennsylvania

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Director
Director
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Joined: 11 Jun 2007
Posts: 637
Samples from the floor of a rock shelter in Pennsylvania [#permalink]

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New post 04 Dec 2007, 16:47
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A
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C
D
E

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Samples from the floor of a rock shelter in Pennsylvania were dated by analyzing the carbon they contained. The dates assigned to samples associated which human activities formed a consistent series, beginning with the present and going back in time, a series that was correlated with the depth from which the samples came. The oldest and deepest sample was dated at 19,650 years before the present, plus or minus 2,400 years. Skeptic, viewing that date of human migration into North America, suggested that the samples could have been contaminated by dissolved "old carbon" carried by percolating groundwater from nearby coal deposits.

Which one of the following considerations, if true, argues most strongly against the suggestion of the skeptics?

(A) No likely mechanism of contamination involving percolating groundwater would have affected the deeper samples from the site without affecting the uppermost sample.

(B) Not every application of the carbon-dating procedure has led to results that have been generally acceptable to scientists.

(C) There is no evidence that people were using coal for fuel at any time when the deepest layer might have been laid down.

(D) No sample in the series, when retested by the carbon-dating procedure, was assigned an earlier date than that assigned to a sample from a layer above it.

(E) No North American site besides the one in Pennsylvania has ever yielded a sample to which the carbon-dating procedure assigned a date that was comparably ancient.

Please explain your answers.
Director
Director
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Joined: 13 Dec 2006
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Location: Indonesia
 [#permalink]

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New post 04 Dec 2007, 16:57
Is it C

Amar
Director
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 [#permalink]

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New post 04 Dec 2007, 19:47
I will post the OA after sometime. Disappointed that not too many ppl are trying this CR. :(
CEO
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Joined: 29 Mar 2007
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Re: CR: Skeptics [#permalink]

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New post 04 Dec 2007, 20:46
eyunni wrote:
Samples from the floor of a rock shelter in Pennsylvania were dated by analyzing the carbon they contained. The dates assigned to samples associated which human activities formed a consistent series, beginning with the present and going back in time, a series that was correlated with the depth from which the samples came. The oldest and deepest sample was dated at 19,650 years before the present, plus or minus 2,400 years. Skeptic, viewing that date of human migration into North America, suggested that the samples could have been contaminated by dissolved "old carbon" carried by percolating groundwater from nearby coal deposits.

Which one of the following considerations, if true, argues most strongly against the suggestion of the skeptics?

(A) No likely mechanism of contamination involving percolating groundwater would have affected the deeper samples from the site without affecting the uppermost sample.

(B) Not every application of the carbon-dating procedure has led to results that have been generally acceptable to scientists.

(C) There is no evidence that people were using coal for fuel at any time when the deepest layer might have been laid down.

(D) No sample in the series, when retested by the carbon-dating procedure, was assigned an earlier date than that assigned to a sample from a layer above it.

(E) No North American site besides the one in Pennsylvania has ever yielded a sample to which the carbon-dating procedure assigned a date that was comparably ancient.

Please explain your answers.


I think its D. Explains that if the skeptics claim were to be true, then there should be several random dates.

sry man been off the verbal forum for awhile.

Been doin paper tests and lookin for jobs....
Director
Director
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Joined: 12 Jul 2007
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 [#permalink]

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New post 04 Dec 2007, 22:46
D is the only one that looks relevant to me.
Director
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Re: CR: Skeptics [#permalink]

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New post 05 Dec 2007, 07:28
eyunni wrote:
Samples from the floor of a rock shelter in Pennsylvania were dated by analyzing the carbon they contained. The dates assigned to samples associated which human activities formed a consistent series, beginning with the present and going back in time, a series that was correlated with the depth from which the samples came. The oldest and deepest sample was dated at 19,650 years before the present, plus or minus 2,400 years. Skeptic, viewing that date of human migration into North America, suggested that the samples could have been contaminated by dissolved "old carbon" carried by percolating groundwater from nearby coal deposits.

Which one of the following considerations, if true, argues most strongly against the suggestion of the skeptics?

(A) No likely mechanism of contamination involving percolating groundwater would have affected the deeper samples from the site without affecting the uppermost sample.

(B) Not every application of the carbon-dating procedure has led to results that have been generally acceptable to scientists.

(C) There is no evidence that people were using coal for fuel at any time when the deepest layer might have been laid down.

(D) No sample in the series, when retested by the carbon-dating procedure, was assigned an earlier date than that assigned to a sample from a layer above it.

(E) No North American site besides the one in Pennsylvania has ever yielded a sample to which the carbon-dating procedure assigned a date that was comparably ancient.

Please explain your answers.


I say D.

Contest was b/w A & D. But A leaves open the possibility that the upper samples are contaminated as well.
VP
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Joined: 22 Nov 2007
Posts: 1080
Re: CR: Skeptics [#permalink]

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New post 06 Dec 2007, 23:22
What is the OA? Can someone explain me everything by a POE ?????
Re: CR: Skeptics   [#permalink] 06 Dec 2007, 23:22
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Samples from the floor of a rock shelter in Pennsylvania

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