Are x and y both positive ?

[its.ur.life]

Are x and y both positive ?
1. 2x - 2y = 1
2. x/y >1

This is a DS Ques.
Ans 3.

My Sol.
1. x - y =1/2
x = -1/2 y = -1
x = 1 y = 1/2

So insufficient.

2. x>y ==> x-y >0
put same vales as above
==> Insufficient.

So my ans is 5.


Kindly explain.

[tim]

you haven't combined the statements to determine whether the answer is C or E. you also don't seem to have analyzed (2) properly..

[abdul_tt]

Here is how I combined Statement 1 & 2

2x-2y=1
x-y=1/2
Dividing LHS by y and RHS by Y; I'm doing this because statement 2 is (x/y)>1

(x-y)/y = 1/2y
x/y - 1 = 1/2y
x/y= 1/2y +1 ------- now putting this in our equation 2

1/2y + 1 > 1
1/2y > 0
This is only possible if Y>0 since 1 is always positive. If y is positive X must be positive. So combining 1 &2 yields us that both x & Y is positive.

[jnelson0612]

Here is how I combined Statement 1 & 2

2x-2y=1
x-y=1/2
Dividing LHS by y and RHS by Y; I'm doing this because statement 2 is (x/y)>1

(x-y)/y = 1/2y
x/y - 1 = 1/2y
x/y= 1/2y +1 ------- now putting this in our equation 2

1/2y + 1 > 1
1/2y > 0
This is only possible if Y>0 since 1 is always positive. If y is positive X must be positive. So combining 1 &2 yields us that both x & Y is positive.

Thanks abdul!

[praks.g]

But by checking the values, I get two answers one x,y> 0 and other x,y<0.

Check the above equations for these 2 scenarios:
x = -0.5 and y = -1.
x = 1 and y = 0.5

Therefore, shouldn't the answer be E. Point me if I am going wrong somewhere.

[jnelson0612]

But by checking the values, I get two answers one x,y> 0 and other x,y<0.

Check the above equations for these 2 scenarios:
x = -0.5 and y = -1.
x = 1 and y = 0.5

Therefore, shouldn't the answer be E. Point me if I am going wrong somewhere.

Check out statement 2:
2. x/y >1

Your set of negative numbers does not fit this equation, so you have to toss it out. Thus, the positives are the only possible option and the answer is C.