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positive integer

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positive integer

by ketkoag » Sat Jul 11, 2009 4:53 am
If x and y are positive, is 3x > 7y?
(1) x > y + 4
(2) -5x < -14y
[spoiler]
here i got B as the answer but the OA is D..
How statement 1 is sufficient?
take y=10, x=30 then 3x=90 and 7x=70
so 3x>7x..
now take y = 10, x = 15, therefore 3x = 45 and 7x = 70
so 3x<7x
please elaborate if i missed something..[/spoiler]
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by Robinmrtha » Sat Jul 11, 2009 5:12 am
Statement 1

(1) x > y + 4
when y is less than 4, i.e. 2 then x is greater than 6
then the equation is 3x>7y: 18> 14 true....
when y is more than 4, i.e. 5 then x is 9
then 27>28 false...
insufficient

Statement 2

(2) -5x < -14y
or 5x>14y
or x>14y/5
or x >2.8y
from the question we have x > 2.3y
Since x >2.8y, then x > 2.3y
Sufficient

Answer B
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by gmat740 » Sat Jul 11, 2009 9:23 am
IMO B
what is the source?
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