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If x and y are positive, is 3x>7y ? 1) x>y+4 2) [#permalink]
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16 Oct 2008, 12:03
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If x and y are positive, is 3x>7y ? 1) x>y+4 2) 5x<14y == Message from GMAT Club Team == This is not a quality discussion. It has been retired. If you would like to discuss this question please repost 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.



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Re: DS QUestion [#permalink]
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16 Oct 2008, 13:06
spiridon wrote: E why? rnemani wrote: If x and y are positive, is 3x>7y ?
1) x>y+4 2) 5x<14y from 2: 5x > 14y 2.5x > 7y is not that suff?
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Re: DS QUestion [#permalink]
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16 Oct 2008, 14:33
I got B as 5x < 14y can be solved to x >14/5 y which show that x> 7/3y.
But the OA is D. I am not sure how



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Re: DS QUestion [#permalink]
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16 Oct 2008, 14:56
D is correct.
we have to prove x > 7/3 y Case 1: x> y+4 y = 0 x > 4 means x > (7/3)* 0 , y=1, x> 5 means x >(7/3 ) * 1 etc... its sufficient. Case 2: x > 14/5 y it can be similarly proven using values .... that its sufficient. hence D.



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Re: DS QUestion [#permalink]
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16 Oct 2008, 15:18
gameCode wrote: D is correct.
we have to prove x > 7/3 y Case 1: x> y+4 y = 0 x > 4 means x > (7/3)* 0 , y=1, x> 5 means x >(7/3 ) * 1 etc... its sufficient. Case 2: x > 14/5 y it can be similarly proven using values .... that its sufficient. hence D. how is st. 1 true? if y = 1, x > 5, then 3x is 15 and 7y is 7. so 3x>7y is true. but if y = 10, x > 14. lets say x = 15 3x is 45, where as 7y is 70.
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Re: DS QUestion [#permalink]
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16 Oct 2008, 16:35
GMAT TIGER wrote: spiridon wrote: E why? rnemani wrote: If x and y are positive, is 3x>7y ?
1) x>y+4 2) 5x<14y from 2: 5x > 14y 2.5x > 7y is not that suff? how did you get 5x >14y from 5x<14y even if you multiply with 1, you will get 5x >14y eg: x = 2, y=1 10<14  TRUE 10>14  TRUE I get E for this question. I am suprised that the OA is D.



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Re: DS QUestion [#permalink]
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16 Oct 2008, 17:04
[quote="rnemani"]If x and y are positive, is 3x>7y ?
1) x>y+4 2) 5x<14y
from 1
( as an extreme measure , though it is mentioned that x,y are+ve i will use y = 0)
from 1
x> 4, say = 5 thus sure 3x>7y...........suff
from 2
5x> 14y ( i will approx devide by 5)
x> 3y ie: 3x>9y thus sure 3x> 7y..........suff
D



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Re: DS QUestion [#permalink]
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16 Oct 2008, 17:21
yezz wrote: rnemani wrote: If x and y are positive, is 3x>7y ?
1) x>y+4 2) 5x<14y
from 1
( as an extreme measure , though it is mentioned that x,y are+ve i will use y = 0)
from 1
x> 4, say = 5 thus sure 3x>7y...........suff
from 2
5x> 14y ( i will approx devide by 5)
x> 3y ie: 3x>9y thus sure 3x> 7y..........suff
D how about when x = 10, y = 5 30 < 35  Not sufficient.



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Re: DS QUestion [#permalink]
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17 Oct 2008, 02:19
yup i agree. Statement 1 is true only for y = 1, 2, 3. From 4 onwards its false. Hence its not sufficient. Sorry for the earlier post.



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Re: DS QUestion [#permalink]
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17 Oct 2008, 03:19
Unless the question has typo, the answer must be E.



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Re: DS QUestion [#permalink]
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17 Oct 2008, 11:33
LiveStronger wrote: GMAT TIGER wrote: spiridon wrote: E why? rnemani wrote: If x and y are positive, is 3x>7y ?
1) x>y+4 2) 5x<14y from 2: 5x > 14y 2.5x > 7y is not that suff? how did you get 5x >14y from 5x<14y even if you multiply with 1, you will get 5x >14y eg: x = 2, y=1 10<14  TRUE 10>14  TRUE I get E for this question. I am suprised that the OA is D. That I sometime do overlooking.
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Re: DS QUestion [#permalink]
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19 Oct 2008, 05:51
[quote="rnemani"]If x and y are positive, is 3x>7y ? 1) x>y+4 2) 5xy+4 say 3x>4y+3y => x>y+4/3 y now if 4/3y7y holds good !! INSUFFI 2)5x x> 14/5y now if this is true and y>0 => x>7/3y may o may not be true !! INSUFFI Consider both : 1) and 2) say x>y+4 since this the positive among the two ,represents overlaping values hence INSUFI to validate the questioin IMO E == Message from GMAT Club Team == This is not a quality discussion. It has been retired. If you would like to discuss this question please repost 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.
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