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# The Earth’s magnetic field has reversed a number of times

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The Earth’s magnetic field has reversed a number of times  [#permalink]

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08 May 2017, 06:34
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35% (medium)

Question Stats:

72% (01:44) correct 28% (01:56) wrong based on 235 sessions

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The Earth’s magnetic field has reversed a number of times in its history. Before the poles actually flip, the magnetic field weakens and the magnetic poles drift away from “true” north and south. On average, the magnetic north and south poles flip about once every 200,000 years. The last time the poles flipped was 780,000 years ago. Therefore, the poles are in the process of reversing.

Which of the following, if true, most strengthens the conclusion that the poles are reversing?

(A) Magnetic north has recently been moving toward closer alignment with “true” north.
(B) Sometimes the magnetic fields go for over one million years without reversing.
(C) The earth’s atmosphere has warmed about one degree Celsius over the past century.
(D) The strength of the magnetic field has declined by over ten percent since 1845, the first year it was measured.
(E) The location of the magnetic poles has remained unchanged for as long as magnetic compasses have been in use.

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Re: The Earth’s magnetic field has reversed a number of times  [#permalink]

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09 May 2017, 23:24
1
Official Explanation.

For this question, you need to strengthen the conclusion that the poles are currently in the process of reversing. Choice A actually weakens the conclusion because the magnetic pole’s shifting away from true north would be a sign of the poles shifting. Choice B also weakens the conclusion, as 780,000, rather than a million, years have passed since the last reversal. Choice E weakens the conclusion as well, because it again suggests stability in the poles. Eliminate C because the warming of the atmosphere isn’t relevant to the reversal of the poles. Choice D is the only answer choice that indicates a lessening of the strength of the magnetic field and a trend toward a reversal of the poles.

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The Earth’s magnetic field has reversed a number of times  [#permalink]

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10 Nov 2017, 20:05
what is the source of this question?
boiled down to A and D.
A cannot be an answer b/c A literally weakens the argument. In A, there is an assumption that the magnetic poles are called North or South based on the location of the magnetic poles.
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The Earth’s magnetic field has reversed a number of times  [#permalink]

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10 Nov 2017, 21:33
rohan2345 wrote:
The Earth’s magnetic field has reversed a number of times in its history. Before the poles actually flip, the magnetic field weakens and the magnetic poles drift away from “true” north and south. On average, the magnetic north and south poles flip about once every 200,000 years. The last time the poles flipped was 780,000 years ago. Therefore, the poles are in the process of reversing.

Which of the following, if true, most strengthens the conclusion that the poles are reversing?

(A) Magnetic north has recently been moving toward closer alignment with “true” north.
(B) Sometimes the magnetic fields go for over one million years without reversing.
(C) The earth’s atmosphere has warmed about one degree Celsius over the past century.
(D) The strength of the magnetic field has declined by over ten percent since 1845, the first year it was measured.
(E) The location of the magnetic poles has remained unchanged for as long as magnetic compasses have been in use.

This question is easy. However, I like this one because it provides some new knowledge about the Earth's magnetic field The Earth's magnetic field is so important to us since it prevents raditions from the Sun. If the Earth lose its magnetic field, we would all die soon.
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Re: The Earth’s magnetic field has reversed a number of times  [#permalink]

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11 Nov 2017, 13:11
broall wrote:
rohan2345 wrote:
The Earth’s magnetic field has reversed a number of times in its history. Before the poles actually flip, the magnetic field weakens and the magnetic poles drift away from “true” north and south. On average, the magnetic north and south poles flip about once every 200,000 years. The last time the poles flipped was 780,000 years ago. Therefore, the poles are in the process of reversing.

Which of the following, if true, most strengthens the conclusion that the poles are reversing?

(A) Magnetic north has recently been moving toward closer alignment with “true” north.
(B) Sometimes the magnetic fields go for over one million years without reversing.
(C) The earth’s atmosphere has warmed about one degree Celsius over the past century.
(D) The strength of the magnetic field has declined by over ten percent since 1845, the first year it was measured.
(E) The location of the magnetic poles has remained unchanged for as long as magnetic compasses have been in use.

This question is easy. However, I like this one because it provides some new knowledge about the Earth's magnetic field The Earth's magnetic field is so important to us since it prevents raditions from the Sun. If the Earth lose its magnetic field, we would all die soon.

It is good to hear a feedback from you, but you should not play with the outside knowledge while doing gmat questions.
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Re: The Earth’s magnetic field has reversed a number of times  [#permalink]

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11 Nov 2017, 20:37
chesstitans wrote:
broall wrote:
This question is easy. However, I like this one because it provides some new knowledge about the Earth's magnetic field The Earth's magnetic field is so important to us since it prevents raditions from the Sun. If the Earth lose its magnetic field, we would all die soon.

It is good to hear a feedback from you, but you should not play with the outside knowledge while doing gmat questions.

If you started learning GMAT, you shouldn't use external knowledge to solve GMAT questions. I do agree.

However, if you get so familiar with GMAT (I mean you understand the GMAT concepts and already know how to solve GMAT questions), additional knowledge does help you much in solving GMAT questions, especially in RC. An tough RC in biology could take much time for some test takers to understand, but it can't make test takers with much knowledge about biology hard to understand. Those test takers could answer all questions correct with just a little time.
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Re: The Earth’s magnetic field has reversed a number of times  [#permalink]

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11 Nov 2017, 23:06
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If you started learning GMAT, you shouldn't use external knowledge to solve GMAT questions. I do agree.

However, if you get so familiar with GMAT (I mean you understand the GMAT concepts and already know how to solve GMAT questions), additional knowledge does help you much in solving GMAT questions, especially in RC. An tough RC in biology could take much time for some test takers to understand, but it can't make test takers with much knowledge about biology hard to understand. Those test takers could answer all questions correct with just a little time.[/quote]

Nah, your argument is invalid, I am afraid so. There is no certain that knowledge in gmat is a fact, or a truth; gmat is all about arguments. Learning additional knowledge from gmat questions will distract you from your plan to improve gmat scores.
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Re: The Earth’s magnetic field has reversed a number of times  [#permalink]

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12 Nov 2017, 02:25
1
chesstitans wrote:
Nah, your argument is invalid, I am afraid so. There is no certain that knowledge in gmat is a fact, or a truth; gmat is all about arguments. Learning additional knowledge from gmat questions will distract you from your plan to improve gmat scores.

LOL, I know what I am talking. GMAT does provide some real knowledge, especially history, biology, astronomy,... So the fact that knowledge in GMAT isn't a fact/truth is totally wrong.

Also, GMAT requires you some basic knowledge. For example, you need to know something about how the companies operate, how to improve profits from cost and revenue, and so on.

Yep, it's true that GMAT questions are all on argument, so we need to use the given information to answer the question, not to use other information outside that question. However, my point is that if we know that knowledge, we could answer that question better. This isn't a must, but an advantage over others. Do you understand my point?
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Re: The Earth’s magnetic field has reversed a number of times  [#permalink]

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12 Nov 2017, 15:13
broall wrote:
chesstitans wrote:
Nah, your argument is invalid, I am afraid so. There is no certain that knowledge in gmat is a fact, or a truth; gmat is all about arguments. Learning additional knowledge from gmat questions will distract you from your plan to improve gmat scores.

LOL, I know what I am talking. GMAT does provide some real knowledge, especially history, biology, astronomy,... So the fact that knowledge in GMAT isn't a fact/truth is totally wrong.

Also, GMAT requires you some basic knowledge. For example, you need to know something about how the companies operate, how to improve profits from cost and revenue, and so on.

Yep, it's true that GMAT questions are all on argument, so we need to use the given information to answer the question, not to use other information outside that question. However, my point is that if we know that knowledge, we could answer that question better. This isn't a must, but an advantage over others. Do you understand my point?

well, the basic knowledge is actually about the fundamental concepts about in a subject. Such things should not be called "knowledge at all".
Knowing more about a subject does not give anyone an advantage at all. For example, I changed my major from studying medical to finance / accounting, then to computer science. Besides, I often watch episodes about the astronomy, and take GE classes in the community college; those classes include history, music, and so on.
Let's say I still have fresh memory about what I have learnt. Clearly, much of my knowings will not be considered knowledge that can be used in the gmat test.
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The Earth’s magnetic field has reversed a number of times  [#permalink]

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12 Nov 2017, 18:25
chesstitans wrote:
broall wrote:
chesstitans wrote:
Nah, your argument is invalid, I am afraid so. There is no certain that knowledge in gmat is a fact, or a truth; gmat is all about arguments. Learning additional knowledge from gmat questions will distract you from your plan to improve gmat scores.

LOL, I know what I am talking. GMAT does provide some real knowledge, especially history, biology, astronomy,... So the fact that knowledge in GMAT isn't a fact/truth is totally wrong.

Also, GMAT requires you some basic knowledge. For example, you need to know something about how the companies operate, how to improve profits from cost and revenue, and so on.

Yep, it's true that GMAT questions are all on argument, so we need to use the given information to answer the question, not to use other information outside that question. However, my point is that if we know that knowledge, we could answer that question better. This isn't a must, but an advantage over others. Do you understand my point?

well, the basic knowledge is actually about the fundamental concepts about in a subject. Such things should not be called "knowledge at all".
Knowing more about a subject does not give anyone an advantage at all. For example, I changed my major from studying medical to finance / accounting, then to computer science. Besides, I often watch episodes about the astronomy, and take GE classes in the community college; those classes include history, music, and so on.
Let's say I still have fresh memory about what I have learnt. Clearly, much of my knowings will not be considered knowledge that can be used in the gmat test.

Well, this seems to be personal opinions. Also, this topic is irrelevant to the question #1 so I will stop here Thank you for opinions.
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The Earth’s magnetic field has reversed a number of times &nbs [#permalink] 12 Nov 2017, 18:25
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