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The popular notion that a tree's age can be determined by counting the

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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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08 Mar 2016, 23:11
"C" gives an additional information. It states another fact. It is not a necessary assumption."Only one day of temperature" also is rather extreme in its tone.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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24 Apr 2016, 07:02
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The popular notion that a tree's age can be determined by counting the number of internal rings in its trunk is generally true.
However, to help regulate the internal temperature of the tree, the outermost layers of wood of the Brazilian ash often peel away when the temperature exceeds 95 degrees Fahrenheit, leaving the tree with fewer rings than it would otherwise have. So if the temperature in the Brazilian ash's environment never exceeded 95 degrees Fahrenheit, its rings would be a reliable measure of the tree's age.

Which of the following is an assumption on which the argument above depends?
(B) Only the Brazilian ash loses rings because of excessive heat...................we are bothered about this particular tree. It does not matter if others lose rings due to some reason.
(C) Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring........duration of heat exposure need not be assumed.
(D) The internal rings of all trees are of uniform thickness.....................thickness is additional information and need not be assumed.

While we can easily eliminate options B, C and D since they are out of scope.
Most of the candidates above(including me) got stuck between A and E.

(A) The growth of new rings in a tree is not a function of levels of precipitation..............TRAP choice. This seems to indicate that during the scenario of more than 95 degrees Fahrenheit temperature tree only loses rings and does not grow them. This seems to divert us towards reverse causality assumption but there is no reason to assume anything like that regarding growth of new rings.

(E) The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is not predictable
This may not look as attractive as option A but is the correct answer and can be veified through negation test.
If the number of rings is predictable then we can easily decide the tree age even if in high temperatures and this collapses the argument.

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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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05 May 2016, 04:56
It's easily E

Premise : Tree loses rings if temp > 95 F
Conclusion : Rings a reliable source only if temp < 95 F

Gap : There is no alternate method of determining the age other than the ring itself.

E perfectly fills that. That loss of rings can't be predicted.

A and C are traps.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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05 May 2016, 05:01
redfield wrote:
Can someone explain to me how C is also wrong?

Last line of statement "So if the temperature in the Brazilian ash's environment never exceeded 95 degrees Fahrenheit, its rings would be a reliable measure of the tree's age."

C directly combats the usage of the word "never" in this statement. So the argument assumes that if the environment ever exceeds 95 degrees then it will lose a ring. Answer choice C is essentially this assumption.

The statement also says before this point ""often peel away" not "always", so by it's own admission the final sentence is harsher than the evidence given.

Hi redfield,

C states that "Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring."

Where does one day come from? You can easily eliminate such options because assumptions can't have facts that are not in the premise or conclusion. If you think about it, maybe even 1 second of temp > 95 F can cause the tree to shed some rings ( Just discussing the options). I have a hard and first rule to ignore any options which carry numerical facts and figures not given in the conc and premise.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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15 May 2016, 08:57
Swagatalakshmi wrote:
The popular notion that a tree's age can be determined by counting the number of internal rings in its trunk is generally true. However, to help regulate the internal temperature of the tree, the outermost layers of wood of the Brazilian ash often peel away when the temperature exceeds 95 degrees Fahrenheit, leaving the tree with fewer rings than it would otherwise have. So if the temperature in the Brazilian ash's environment never exceeded 95 degrees Fahrenheit, its rings would be a reliable measure of the tree's age.

Which of the following is an assumption on which the argument above depends?
(A) The growth of new rings in a tree is not a function of levels of precipitation.
(B) Only the Brazilian ash loses rings because of excessive heat.
(C) Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring.
(D) The internal rings of all trees are of uniform thickness.
(E) The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is not predictable

We have several assumptions here:
1. The reliability of the method described depends on the number of internal rings. Hence the assumption implied is that the number of rings does not changes.
2. There isn't another factor that can influence the mentioned system reliability.

[X] - A - precipitation is not relevant to the discuss, and hence out of scope.
[X] - B - this does not influence the conclusion.
[X] - C - not relevant.
[X] - D - this is not relevant.
[V] - E - If the number of rings is predictable, then the number of rings can changes, and hence this negates the assumption. so this statement must be true for the conclusion to hold.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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30 May 2016, 15:46
I got this wrong initially, but the more I think about it, I understand why E works.

When doing the negation the proper negation of choice E is: The number of rings that will be lost when the temperature DOES NOT exceed 95 degrees Fahrenheit is not predictable

The conclusion clearly says that when temp is <95 degrees its predictable. Thus, negating E makes the conclusion fall apart, so E is the answer.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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01 Oct 2016, 12:48
The argument concludes that " rings are not a reliable measure for the age if temp exceeds 95 " . The basis of the conclusion is when temp goes beyond 95 rings are lost

(A) The growth of new rings in a tree is not a function of levels of precipitation.- even if growth of new ring is the function of levels of precipitation, it can still be counted and it can still be reliable indicator provided temp is <95. doesn't shatter my conclusion

(B) Only the Brazilian ash loses rings because of excessive heat. - so what?

(C) Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring. - doesn't matter how many days it takes to lose the ring, the ring can still be a reliable measure of the age.

(D) The internal rings of all trees are of uniform thickness. - irrelevant

(E) The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is not predictable - ok! lets negate - if they can be counted when temp >95, then why the whole fuss, just add them up and itll be a reliable indicator even when temp is >95, shatters the conclusion - CORRECT
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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30 Dec 2016, 10:10
No way E is correct.
Conclusion-If the temperature in the Brazilian ash's environment never exceeded 95 degrees Fahrenheit, its rings would be a reliable measure of the tree's age.
Negate E:The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is predictable.
This choice doesn't break the conclusion in any way.So E is not correct.

I think there is a typo in the question.I checked on other sites, and the correct version seems to be this,
The popular notion that a tree's age can be determined by counting the number of internal rings in its trunk is generally true. However, to help regulate the internal temperature of the tree, the outermost layers of wood of the Brazilian ash often peel away when the temperature exceeds 95 degrees Fahrenheit, leaving the tree with fewer rings than it would otherwise have. So ONLY if the temperature in the Brazilian ash's environment never exceeds 95 degrees Fahrenheit will its rings be a reliable measure of the tree's age.

The version of the question in the OP omits the word 'only', which is quite important to get the correct answer.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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01 Oct 2017, 10:28
sweet_deals wrote:
I'm going with F, none of the above.

The conclusion states that the tree's age can be reliably determined by the rings. An approiate assumption would be:
The "Brazilian ash" grows at a rate that is consistent with other trees, whose age can be determined by the number of rings in it's trunk".

Bringing precipitation into the equation is out of scope.

IMO, this is a garbage question.

:D It is a good question

(A) The growth of new rings in a tree is not a function of levels of precipitation. unrelated
(B) Only the Brazilian ash loses rings because of excessive heat. does not matter
(C) Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring. Even if it takes 1 or more days we are still going to lose the count . not an assumption
(D) The internal rings of all trees are of uniform thickness. We do not care about thickness
(E) The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is not predictable. Correct. If it is predictable , then we can count the number of the days with more than 95 degree and count the number of rings lost.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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10 Oct 2017, 07:55
E is correct.

The conclusion is that the rings will be a reliable measure only if the temperature never exceeds 95 degrees. This is true only if there is no way to predict how many rings would be lost when the temperature does exceed 95 degrees. (If it were possible to predict this, one might be able to assess the age of a tree using its rings even if the temperature had exceeded 95 degrees.)
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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10 Oct 2017, 18:00
The popular notion that a tree's age can be determined by counting the number of internal rings in its trunk is generally true. However, to help regulate the internal temperature of the tree, the outermost layers of wood of the Brazilian ash often peel away when the temperature exceeds 95 degrees Fahrenheit, leaving the tree with fewer rings than it would otherwise have. So if the temperature in the Brazilian ash's environment never exceeded 95 degrees Fahrenheit, its rings would be a reliable measure of the tree's age.

Which of the following is an assumption on which the argument above depends?
(A) The growth of new rings in a tree is not a function of levels of precipitation. -We are interested in the peeling of rings and not in the growth of the rings. Out of scope.
(B) Only the Brazilian ash loses rings because of excessive heat. -We are not worried about the other trees.
(C) Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring. -If this were the case, then we would be able to identify the age of tree even when the temperature exceeds 95 degrees, since as per the statement "a" ring (only one ring) is lost on a day having temperature greater than 95 degrees. Besides, this is just a fact set stating that the requirement for reduction in tree's rings. Irrelevant or, at best, weakener.
(D) The internal rings of all trees are of uniform thickness. -Out of scope
(E) The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is not predictable -Correct. If we can't predict this, then it means that on a day with temperature greater than 95 degree we can't determine the number of rings lost, thus we need a day with temperature less than 95 degree to find out the exact number of rings in the tree.
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Re: The popular notion that a tree's age can be determined by counting the [#permalink]

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23 Oct 2017, 08:23
Swagatalakshmi wrote:
The popular notion that a tree's age can be determined by counting the number of internal rings in its trunk is generally true. However, to help regulate the internal temperature of the tree, the outermost layers of wood of the Brazilian ash often peel away when the temperature exceeds 95 degrees Fahrenheit, leaving the tree with fewer rings than it would otherwise have. So if the temperature in the Brazilian ash's environment never exceeded 95 degrees Fahrenheit, its rings would be a reliable measure of the tree's age.

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

(A) The growth of new rings in a tree is not a function of levels of precipitation.

(B) Only the Brazilian ash loses rings because of excessive heat.

(C) Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring.

(D) The internal rings of all trees are of uniform thickness.

(E) The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is not predictable

OFFICIAL EXPLANATION

The author concludes that one will only be able to determine the age of a Brazilian ash by counting its rings if the temperature in the tree's environment never exceeds 95 degrees Fahrenheit. The author bases this conclusion on the fact that the tree loses rings when the temperature exceeds that level. However, if the number of rings lost by a Brazilian ash at high temperatures could be predicted, then it might be possible to determine the age of a tree even if the temperature exceeds 95 degrees. The author assumes that it is not possible to predict the number of rings lost when the temperature exceeds 95 degrees Fahrenheit.

(A) The argument says nothing about precipitation. This answer choice is out of scope since it would require a number of other assumptions to make it relevant to the argument's conclusion.

(B) Whether other trees share this feature is irrelevant; the argument focuses only on the Brazilian ash.

(C) This choice says that one day of temperatures above 95 degrees = one ring lost. If this is true, then we might actually be able to predict the number of rings lost (if we also know on how many days the temperature exceeded 95 degrees). This hurts the author’s argument; therefore, it cannot be an assumption on which the author depends.

(D) The thickness of the rings is irrelevant.

(E) CORRECT. The conclusion is that the rings will be a reliable measure only if the temperature never exceeds 95 degrees. This is true only if there is no way to predict how many rings would be lost when the temperature does exceed 95 degrees. (If it were possible to predict this, one might be able to assess the age of a tree using its rings even if the temperature had exceeded 95 degrees.)
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Re: The popular notion that a tree's age can be determined by counting the   [#permalink] 23 Oct 2017, 08:23

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