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# M01-17

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Director
Joined: 11 Feb 2015
Posts: 558

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05 Jul 2018, 03:21
1
Only thing I would like to highlight once again for this problem is that have a set of numbers to test on each and every DS question. For statement (1) it was very important to test for zero. It does not strike naturally for this statement that m could be zero.

Hence develop a habit to test numbers systematically. Use a standard set of numbers during your practice sessions so that this becomes a habit. After reading the constraints mentioned in question stem and the 2 statements, you could test for (assuming no constraints) -2,$$\frac{-3}{2}$$,-1,$$\frac{-1}{2}$$,0,$$\frac{1}{2}$$,1,$$\frac{3}{2}$$ and 2.

Please read my overall understanding on DS questions and few useful tips:-

https://gmatclub.com/forum/data-suffici ... l#p2073589
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Manish

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Joined: 09 Apr 2018
Posts: 20
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GMAT 1: 690 Q47 V38
GMAT 2: 710 Q49 V36
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20 Jul 2018, 06:07
Hi,

|x| = -x if x<0
|x| = x if x>0

In this scenario |-m| = -(-m) = m if -m<0, hence m>0
|-m| = -m if -m>0, Hence m<0

According to statement 1, |-m| = -m, hence -m>0, hence m<0, Hence statement 1 is sufficient.
Please let me know why is thought process incorrect?
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Joined: 02 Sep 2009
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20 Jul 2018, 09:35
Fervids77 wrote:
Hi,

|x| = -x if x<0
|x| = x if x>0

In this scenario |-m| = -(-m) = m if -m<0, hence m>0
|-m| = -m if -m>0, Hence m<0

According to statement 1, |-m| = -m, hence -m>0, hence m<0, Hence statement 1 is sufficient.
Please let me know why is thought process incorrect?

I think this is explained in the solution as well as in the discussion. Please re-read.
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Posts: 20
Location: India
GMAT 1: 690 Q47 V38
GMAT 2: 710 Q49 V36
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20 Jul 2018, 09:45
Hi,

I re read the solution, but unable to understand the flaw in my logic
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20 Jul 2018, 09:54
Fervids77 wrote:
Hi,

I re read the solution, but unable to understand the flaw in my logic

$$|m|=-m$$, means that $$m\leq 0$$, so $$m$$ could be either negative or zero. Notice that $$|m|=-m$$ holds if m = 0 too.
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Joined: 09 Apr 2018
Posts: 20
Location: India
GMAT 1: 690 Q47 V38
GMAT 2: 710 Q49 V36
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20 Jul 2018, 10:03
Hi,

Thanks for the response. It is clear now
So if the question was is m>=0 then statement would be sufficient
Re: M01-17 &nbs [#permalink] 20 Jul 2018, 10:03

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# M01-17

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