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What is the value of n^2?

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Intern
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Joined: 02 Jul 2013
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GMAT Date: 01-17-2014
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What is the value of n^2?  [#permalink]

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New post 03 Dec 2013, 09:48
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A
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  5% (low)

Question Stats:

77% (00:38) correct 23% (00:42) wrong based on 279 sessions

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What is the value of n^2?

(1) n = |n|
(2) |n| = 1

Please help me understand how to approach such problems. I always think i understand them, then when I attempt a similar question i fail :cry:
Magoosh GMAT Instructor
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Re: what is the value of n^2  [#permalink]

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New post 03 Dec 2013, 15:07
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1
mumbijoh wrote:
what is the value of n^2?
a) n=|n|
b) |n|=1

Please help me understand how to approach such problems. I always think i understand them, then when I attempt a similar question i fail :cry:

Dear mumbijoh,
I'm happy to help. :-)

What's challenging about this question is: it's a deeply conceptual and logical question. You really have to think about this NOT in terms of any rules or formulas, but in terms of the fundamental mathematical meanings. See this blog:
http://magoosh.com/gmat/2013/mathematic ... -the-gmat/

Statement #1: n=|n|
This is true of every positive number as well as zero. The range is too wide --- (n^2) could take any value between 0 and infinity. This statement, alone and by itself, is not sufficient.

Statement #1: |n|=1
This allows two possibilities for n, either n = +1 or n = -1. If we had to find the value of n itself, this would not be enough. BUT, all we need is the value of n^2, and whether n = +1 or n = -1, we know that (n^2) = +1. Thus, we can answer the prompt. This statement, alone and by itself, is sufficient.

Answer = (B)

Does all this make sense?
Mike :-)
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Mike McGarry
Magoosh Test Prep


Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)
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Re: what is the value of n^2  [#permalink]

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New post 03 Dec 2013, 22:51
Thanks Mike.I have understood.
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Re: What is the value of n^2?  [#permalink]

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New post 31 Mar 2015, 02:23
mumbijoh wrote:
What is the value of n^2?

(1) n = |n|
(2) |n| = 1

Please help me understand how to approach such problems. I always think i understand them, then when I attempt a similar question i fail :cry:


Using statement (1): n = |n|
Using the above statement we can only know that n will always be greater than equal to 0.
But we don't have any unique value of n.
Hence this statement alone is not sufficient.

Using statement (2): |n| = 1
Here n can be +1 or -1.
In any case, n^2 = 1 always.
Hence we have a unique value.

So statement (2) alone is sufficient.

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Re: What is the value of n^2?  [#permalink]

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New post 09 Jul 2017, 05:31
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What is the value of n^2?

(1) n = |n|
(2) |n| = 1

Solution:

Statement 1: n can be 1,2,3,4..... etc n^2 varies accordingly.

Statement 2: n can be +1 or -1. But in both the case, the answer of n^2 is 1

Therefore the answer is B.
GMAT Club Bot
Re: What is the value of n^2?   [#permalink] 09 Jul 2017, 05:31
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