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# Is 1/p > r/(r^2+2) ? 1. p = r 2. r > 0 Can

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Senior Manager
Joined: 19 Nov 2009
Posts: 261
Is 1/p > r/(r^2+2) ? 1. p = r 2. r > 0 Can  [#permalink]

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Updated on: 21 Mar 2010, 01:17
2
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(N/A)

Question Stats:

80% (01:00) correct 20% (00:39) wrong based on 57 sessions

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Is $$\frac{1}{p} > \frac{r}{(r^2+2)}$$ ?

1. p = r
2. r > 0

Can anyone pls. explain why the answer is C ?

Originally posted by nsp007 on 20 Mar 2010, 23:17.
Last edited by nsp007 on 21 Mar 2010, 01:17, edited 3 times in total.
Senior Manager
Joined: 30 Aug 2009
Posts: 275
Location: India
Concentration: General Management
Re: Gmat Prep DS question !  [#permalink]

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21 Mar 2010, 00:49
nsp007 wrote:
Is $$\frac{1}{p} > \frac{r}{(r+2)}$$ ?

1. p = r
2. r > 0

Can anyone pls. explain why the answer is C ?

stmnt1 - p=r = 1 we get 1/1 > 1/ (1+2) => 1>1/3 - suff

p=r = -3 => 1/-3 > -3> (-3 +2) => -1/3 > 3 insuff

stmnt2 - r>0 we have no info about p hence insuff

taking together have p=r > 0

p=r = 1 we get 1/1 > 1/ (1+2) => 1>1/3 - suff
p = r = 8 we get 1/8 > 8/ (8+2) => 1/8 > 8/10 insuff

will go with E
Senior Manager
Joined: 19 Nov 2009
Posts: 261
Re: Gmat Prep DS question !  [#permalink]

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21 Mar 2010, 00:57
Sorry for the typo in the problem statement....

Here's the correct version !

Is $$\frac{1}{p} > \frac{r}{(r^2+2)}$$ ?

1. p = r
2. r > 0

Can anyone pls. explain why the answer is C ?
Senior Manager
Joined: 30 Aug 2009
Posts: 275
Location: India
Concentration: General Management
Re: Gmat Prep DS question !  [#permalink]

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21 Mar 2010, 01:02
nsp007 wrote:
Sorry for the typo in the problem statement....

Here's the correct version !

Is $$\frac{1}{p} > \frac{r}{(r^2+2)}$$ ?

1. p = r
2. r > 0

Can anyone pls. explain why the answer is C ?

stmnt1 - p=r = 1 we get 1/1 > 1/ (1^2+2) => 1>1/3 - suff

p=r = -3 => 1/-3 > -3> ([-3]^2 +2) => -1/3 > -3/11 insuff

stmnt2 - r>0 we have no info about p hence insuff

taking together have p=r > 0

p=r = 1 we get 1/1 > 1/ (1^2+2) => 1>1/3 - suff
p = r = 8 we get 1/8 > 8/ (8^2+2) => 1/8 > 8/66 suff

will go with C
Manager
Joined: 05 Mar 2010
Posts: 180
Re: Gmat Prep DS question !  [#permalink]

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21 Mar 2010, 03:58
1/p > r/r^2 +2
this condition satisfy only when p=r and both are positive

will go with C
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Posts: 49385
Re: Gmat Prep DS question !  [#permalink]

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21 Mar 2010, 04:36
nsp007 wrote:
Is $$\frac{1}{p} > \frac{r}{(r^2+2)}$$ ?

1. p = r
2. r > 0

Can anyone pls. explain why the answer is C ?

Algebraic approach:

Is $$\frac{1}{p}>\frac{r}{r^2 + 2}$$?

(1) $$p=r$$ --> is $$\frac{1}{r}>\frac{r}{r^2+2}?$$ --> as $$r^2+2$$ is always positive, multiplying inequality by this expression we'll get: is $$\frac{r^2+2}{r}>r?$$ --> is $$r+\frac{2}{r}>r?$$ --> is $$\frac{2}{r}>0?$$ This inequality is true when $$r>0$$ and not true when $$r<0$$. Not sufficient.

(2) $$r>0$$. Not sufficient by itself.

(1)+(2) As from (2) $$r>0$$, then $$\frac{2}{r}>0$$ is true. Sufficient.

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Posts: 261
Re: Gmat Prep DS question !  [#permalink]

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22 Mar 2010, 17:14
thanks for the explanation !
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Re: Is 1/p > r/(r^2+2) ? 1. p = r 2. r > 0 Can  [#permalink]

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02 Jul 2018, 22:33
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Re: Is 1/p > r/(r^2+2) ? 1. p = r 2. r > 0 Can &nbs [#permalink] 02 Jul 2018, 22:33
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