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Source: — Data Sufficiency |
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by pradeepkaushal9518 » Sun Apr 25, 2010 4:30 am
if -2x>3y is x negative

1.y>0
-2x>3y

since y is >o so in order to -2x>3y x has to be negative ( sufficient)

2.2x+5y-20=0

2x+5y=20
2x= 20-5y
-2x=5y-20
it means 5y-2o> 3y

puting y=1 -15>3 which is wrong so x has to be negative so that -2x>3y it is also sufficeint

then the answer will be D

sumbody can confirm my logic
here we cant say anything that x is negative so insufficient

so imo A is the answer
Last edited by pradeepkaushal9518 on Sun Apr 25, 2010 5:03 am, edited 1 time in total.
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by nisha.menon294 » Sun Apr 25, 2010 4:33 am
OA is D
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by pradeepkaushal9518 » Sun Apr 25, 2010 4:41 am
sumbody can rectify me i am new to DS
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by neoreaves » Sun Apr 25, 2010 5:00 am
ok lets look at the constraints

-2x > 3y

-2/3x > y or x < -3/2y

and the question asks us if x < 0 ?

1) y >0

we know that x < -3/2y so x <0 if y >0 thus sufficient

2) 2x + 5y - 20 = 0

5y = 20-2x
y = 4 - 0.4x

now plug this back into the constraint

-2x/3 > 4 - 0.4x

-2x/3 + 4x/10 > 4

-8x/30 > 4

x < 4(-30/8)

x< -15

Hence sufficient

Thus the answer should be D
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by akhpad » Sun Apr 25, 2010 5:13 am
I also agree with D.
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by harshavardhanc » Sun Apr 25, 2010 5:22 am
nisha.menon294 wrote:If -2x>3y , is X negative

1)y>0
2)2x+5y-20=0

from the stem :

-2x>3y or 2x < -3y and it asks us if x<0.

statement 1:

y>0. so, the right side of the inequality above becomes a negative number and which is greater than 2x. This means, x itself has to be a negative number. Thus, we got our answer. Sufficient.

Statement 2 :

2x+5y =20

as 2x is less than -3y. substituting -3y in statement 2 gives us :

-3y + 5y > 20

or 2y > 20 or y>10 . basically, y is positive. with the same reasoning used for statement 2, x becomes negative. hence sufficient.

hence, D.
Regards,
Harsha
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