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# do not understand OA for a GmatPrep1 - inequality

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Manager
Joined: 19 Aug 2006
Posts: 226
do not understand OA for a GmatPrep1 - inequality [#permalink]

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16 Mar 2009, 19:09
Hey all,
I do not quite understand the OA for the problem below.

I think for statement 1) we can assume that x and y are either:

positive-positive=0.5
pos.-neg.=0.5 (e.g. 0.2-(-0.3)=0.5)
neg-neg=0.5 (e.g. -0.3-(-0.8)=0.5)
not suffic.

statement 2) tells us x and y have the same signs, so it's not suffic.

Combining both of 1) and 2) should still give us 'not suffic.', because both statement 1) and 2) tell us x and y can be both positive or negative.

OA is C. What am I missing here? Do I need more coffee?? Could someone please help?

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Senior Manager
Joined: 08 Jan 2009
Posts: 310
Re: do not understand OA for a GmatPrep1 - inequality [#permalink]

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16 Mar 2009, 19:43
stmt 1 tells us

2x -2y = 1 so x = y +1/2

from above we can says x > y.
x and y can be both positive or negative. Insufficient

stmt 2 tells us

(x/y) > 1 that means x and y can be both positive or negative. Insufficient.

combining both
y<0 x/y > 1 x<y
y>0 x/y > 1 x>y. clearly x and y are both positive,

Walkers graphical method is good.Please refer it.
SVP
Joined: 07 Nov 2007
Posts: 1738
Location: New York
Re: do not understand OA for a GmatPrep1 - inequality [#permalink]

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16 Mar 2009, 21:48
1. X,Y both can be positive
or x is +ve y is -ve

not sufficient
2)
x,y both must be +ve or -ve
not sufficient

combined

2x-2y=1 --> x/y -1= 1/2y

1/2y = x/y-1 = +ve (since x/y >1 )

so y +ve .. obvisouly x must be +Ve

C.
_________________

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Manager
Joined: 19 Aug 2006
Posts: 226
Re: do not understand OA for a GmatPrep1 - inequality [#permalink]

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17 Mar 2009, 07:25
Guys,
Can anyone explain why for statement 1) the following is not true:

2x-2y=1 => 2(x-y)=1 => x-y=0.5
pos.-neg.=0.5
e.g. 0.2-(-0.3)=0.5

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
Re: do not understand OA for a GmatPrep1 - inequality   [#permalink] 17 Mar 2009, 07:25
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# do not understand OA for a GmatPrep1 - inequality

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