Hi All,

This DS question involves a bit of math and a bit of Number Properties; by TESTing VALUES, you can prove what the correct answer is.

We're ask if (-Y)/2 is greater than Y^2. This is a YES/NO question.

Fact 1: Y^2 = 1/25

Here, we're dealing with a straight-forward equation with two solutions: 1/5 and -1/5. We still have to make sure that we're answering the question that's ASKED though:

IF....

Y = 1/5

(-1/5)/2 = -1/10

-1/10 is NOT greater than 1/25 so the answer to the question is NO

IF....

Y = -1/5

(-(-1/5))/2 = 1/10

1/10 IS greater than 1/25 so the answer to the question is YES

Fact 1 is INSUFFICIENT

Fact 2: |Y| = -Y

This Fact tell us that Y CANNOT be positive. It can be 0 or ANY negative number though.

IF....

Y = -1/5

(-(-1/5))/2 = 1/10

1/10 IS greater than 1/25 so the answer to the question is YES

IF...

Y = 0

0/2 is NOT greater than 0 so the answer to the question is NO

Fact 2 is INSUFFICIENT

Combined, we know....

Y = 1/5 or -1/5

Y is 0 or ANY negative

There's only 1 value that fits both Facts: -1/5....so the answer to the question is ALWAYS YES.

Combined, SUFFICIENT

Final Answer:

GMAT assassins aren't born, they're made,

Rich

Missed the case that y could be zero. Good explanation