DS - Word problem [confusing]

Question

Not convinced with OA. Let's see wht Forum guys have to say

GODSPEED!

maliyeci · Answer

1) insuff. 
say
x=-1, y=-1,5
2x-2y=1
or
x=2, y=1,5
2x-2y=1

2)insuff
x/y>1 means absolute value of x > absolute value of y and their sign is same (both +, or -)
say
x=1,5
y=1
x/y>1
or
x=-2
y=-1
x/y>1

together suff.
2x-2y=1 means x is greater than y
x/y>1 means absolute value of x is greater than absolute value of y and their sign is same
if x is greater than y and absolute value of x is greater than absolute value of y then x is positive. Since we know their sign is same. This makes both positive.

C

GODSPEED · Answer

I'm tempted to pick up C....
1. x-y=1/2
2. x/y>1 i.e. x-y>0
So, solving for GIVEN conditions 1 & 2 together

x=1 & y=1/2
X=-1/2 & y=-1

So i picked up E....OA is C...Explain??

yezz · Answer

a)2x-2y = 1
b) x/y>1

from 1

x-y = 1/2 ie: a) x,y both +ve and /x/>/y/ or b) x,y both -ve , /y/>/x/ or c) x +ve, y -ve where /x/,/y/<1/2...insuff

from 2

x/y>1 ie: both have the same sign however /x/>/y/.......insuff

both

is case a from 1........suff...........C

gmate2010 · Answer

1.) x - y = 1/2 ; draw a straight line on a coordinate plane. this line will pass through 1st quadrant,3rd quadrant nd 4rth quadrant..when it passes thru 1st quadrant then, x > 0 and y > 0
2nd quadrant then, x > 0 and y < 0
3rd quadrant then, x < 0 and y < 0
Insufficient

2.) \(\frac{x}{y}\) > 1 ..x = -2 ; y = -1 &x = 2 ; y = 1 Hence, insufficient.

both;
=> \(x = y + \frac{1}{2}\)

=> \(\frac{(2y+1)}{2y} > 1\)
=> 1 + 1/2y > 1
=> y > 0, hence, x > 0 sufficient..

dolly12 · Answer

I think 'C' is wrong

1. plug in x = -2 and y = -2.5 -> 2x-2y = 1 and x/y > 1 (-ve number divided by negative will change inequality sign)

it suffice both conditions.

2. plug in x = 2.5 and y = 2 -> 2x -2y = 1 and x/y > 1

it suffice both negative and postive numbers. So I will pick up 'E'.

Where did you get this question from?? If it is not from official guide or realiable source then chances of OA going wrong are high...

gmate2010 · Answer

(-ve number divided by negative will change inequality sign)
who told you this thing? negative sign get cancelled out with another negative sign, no impact on inequality..answer should be C only..

Bunuel · Answer

With graphic approach I also get E.

gmate2010 · Answer

can you please tell us your graphical approach?

mnpqxyzt · Answer

C is correct. You can see the explanation of gmat2010. I solve this problem the same way.

Bunuel · Answer

My mistake it should be "with graphic approach I also get C". Both statement together are sufficient. Sorry.

Unfortunately I don't know how to post graphs here. So I try to explain.

(1) We should draw x/y=1; x/y>1 gives us two green areas of (x,y) where (x,y) can either both positive or both negative.
(2) Drawing the line 2x-2y=1 we have the line of (x,y) solution that not sufficient to answer the question. (x,y can be negative and positive)

But if we combine (1) and (2) we have segment with only positive solutions of (x,y).

gmate2010 · Answer

I totally agree, Answer should be C..

GODSPEED · Answer

OA ic C

Property of inequalities....: -ve number divided by negative will change inequality sign

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DS - Word problem [confusing]

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