Data Sufficiency

Please see problem below the answer is B, can someone explain?

w+x<0 is w-y>0?
a) x+y<0
b) y< x< w

Thanks!

From the statement: if w + x < 0, then w < -x or -w > x. We can infer that one is a +ve number and one is a -ve number, but we don't know which is which.

We're asked if w - y > 0. Put another way, is w > y?

Stem 1: Not sufficient. We still don't know whether W is +ve or -ve.

x + y < 0 means that x < -y.

Stem 2: Sufficient. "y < x < w" tells us that W is positive, so X must be negative (as we inferred from the main statement above). It also follows that W is > Y.

Thanks, seems easy once you explain it!!

i still have a small doubt..

w+x<0....1 (given)
y+x<0...2 (from statement 1)

1-2 gives w-y<0
therefore w<y

therefore statement 1 is sufficient,,,,,let me know whats wrong here

M still awaiting for a response...Can someone help me clear my doubt?

raju232007 wrote:i still have a small doubt..

w+x<0....1 (given)
y+x<0...2 (from statement 1)

1-2 gives w-y<0

Firstly 1-2 cannot give you w-y<0

you can never subtract the two inequalities, you can only add!

therefore, you cannot subtract w+x <0 and y+x<0.

Hope this helps.

Thnx..i really appreciate your help..what source do you refer to for inequalities and number properties?

Azntycoon wrote:From the statement: if w + x < 0, then w < -x or -w > x. We can infer that one is a +ve number and one is a -ve number, but we don't know which is which.

Both can be negative also.

We're asked if w - y > 0. Put another way, is w > y?

Stem 1: Not sufficient. We still don't know whether W is +ve or -ve.

x + y < 0 means that x < -y.

Stem 2: Sufficient. "y < x < w" tells us that W is positive, so X must be negative (as we inferred from the main statement above). It also follows that W is > Y.

Tarnbir wrote:Please see problem below the answer is B, can someone explain?

w+x<0 is w-y>0?
a) x+y<0
b) y< x< w

Thanks!

I solved it by taking diff eg and @800 is rite..coz numbers can be -ve also.

let w = -10, x =-20(acc to b)
y = -30 . So, w-y >0 ...true

if w= 10 , x = -15 , y = -20(Consdring that w+x has to be -ve so if w is +ve , x has to be bigger no than w and with -ve sign and acc to b, y should be less than x , so taking y bigger no,)
w-y > 0 ...true.

if w = -10 and x = 5,w+x<0 holds but b fails so, w > x

Thas y....Ans is B
hope it helps....
wt do u say @800..

we are given w+x is -ve and
we need to prove w>y

A
x+y is -ve
w+x is -ve
we can not derive any relation between x and y

B
it clearly states y<w
[no need to consider -ve / +ve]

so the Ans is B