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x and y both positive?

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Source: — Data Sufficiency |

by shovan85 » Wed Sep 29, 2010 10:29 am
IMO C

from 2 and 1

x>y taking x and y both positive
say x=1, y=0.5 => 2x-2y = 1.
Or
x<y taking x an y both negative
and when x<y there will be no case 2x-2y=1 as 2x < 2y .

So we can say if both x and y are positive.

What is OA?
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by Fractal » Wed Sep 29, 2010 11:41 am
shovan85 wrote:IMO C

from 2 and 1

x>y taking x and y both positive
say x=1, y=0.5 => 2x-2y = 1.
Or
x<y taking x an y both negative
and when x<y there will be no case 2x-2y=1 as 2x < 2y .

So we can say if both x and y are positive.

What is OA?
thx for your explanation, but i don't understand it ;-)

answer: c
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by shovan85 » Wed Sep 29, 2010 11:49 am
from option 2
either both x and y will be positive or both will be negative.
if positive x>y
if negative x<y as sign will change.

now with this data if you want to validate option 1 then x>y will satisfy not x <y.
so u got a concrete answer that x and y are positive.

hope this helps
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by kvcpk » Wed Sep 29, 2010 12:02 pm
Fractal wrote:(1) 2x - 2y = 1
(2) x/y > 1

neither statement alone is sufficient. does anybody know a good way to check
whether the statements together are sufficient?

thx
Can you tell what the question is? I can only see 2 stmts. What is the question asking for?
"Once you start working on something,
don't be afraid of failure and don't abandon it.
People who work sincerely are the happiest."
Chanakya quotes (Indian politician, strategist and writer, 350 BC-275BC)
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by Fractal » Wed Sep 29, 2010 12:06 pm
kvcpk wrote:
Fractal wrote:(1) 2x - 2y = 1
(2) x/y > 1

neither statement alone is sufficient. does anybody know a good way to check
whether the statements together are sufficient?

thx
Can you tell what the question is? I can only see 2 stmts. What is the question asking for?
are x and y both positive?
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by kvcpk » Wed Sep 29, 2010 12:19 pm
Fractal wrote:(1) 2x - 2y = 1
(2) x/y > 1

neither statement alone is sufficient. does anybody know a good way to check
whether the statements together are sufficient?

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

Let X and Y both be negative.
implies x<0, y<0

When an inequality is multiplied by negative value, its inequality sign changes.

x/y >1

Multiply by y [y is negative]
Hence x<y
which means x-y<0
but x-y =1/2 >0 [according to stmt1]
Hence X and Y both cant be negative

Let x be positive and y be negative.
Same situation as above arises.

Let x be negative and y be positive.
x/y>1
x>y
But a negative value can never be greater than a positive value.
hence this possibility is also lost.

only left out possibility is both are positive.

We dont have to check it. But let us see how it goes.

x>0,y>0
x/y>1
x>y
x-y>0
x-y = 1/2
All the stmts are satisfied.


Hope this helps!!
"Once you start working on something,
don't be afraid of failure and don't abandon it.
People who work sincerely are the happiest."
Chanakya quotes (Indian politician, strategist and writer, 350 BC-275BC)
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by ankur.agrawal » Wed Sep 29, 2010 1:26 pm
Can we do it this way:

2x-2y=1 can be reframed as;

2(x-y) =1; So (x-y) = 1/2;-------(1)

& from 2;

(x/y)-1>0

(x-y)/y>0

Now since x-y=1/2 means x>y

& since (x-y)/y>0 y has to be + since x-y is positive.

Hence both are positive.

DOES THAT MAKES SENSE?
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by HPengineer » Wed Sep 29, 2010 8:37 pm
@ankur.agrawal

i solved it same as you..im also wondering if its dangerous to solve this way...
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by [email protected] » Wed Oct 20, 2010 9:53 pm
IMO E:
St:1: x-y=0.5
St 2: x>y
poss options.. x=0;y=-0.5
x can be either positive o negative right?? hence not sufficient
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by diebeatsthegmat » Thu Oct 21, 2010 10:24 am
[email protected] wrote:IMO E:
St:1: x-y=0.5
St 2: x>y
poss options.. x=0;y=-0.5
x can be either positive o negative right?? hence not sufficient
ohh this is confusing... some books say O is not negative or positive.. its just zero...
so i think 0 is not consider here....
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by shovan85 » Thu Oct 21, 2010 10:33 am
[email protected] wrote:IMO E:
St:1: x-y=0.5
St 2: x>y
poss options.. x=0;y=-0.5
x can be either positive o negative right?? hence not sufficient
After combining both if you consider x=0;y=-0.5 then how will you agree with the second option which says x/y > 1 as from ur choices x/y = 0 which is < 1.

Hope this makes sense
If the problem is Easy Respect it, if the problem is tough Attack it
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by [email protected] » Thu Oct 21, 2010 7:14 pm
After combining both if you consider x=0;y=-0.5 then how will you agree with the second option which says x/y > 1 as from ur choices x/y = 0 which is < 1.
Ah shovan thanks man..
t prob dr i realised.. i multiplied the inequality not considering the sign o it..
this is a big no no.. thanks anyway
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