Manhattan Question Set # 5

Hi richachamption,

To start, this should be in the DS Forum. That having been said, this prompt can be solved rather easily by TESTing VALUES.

We're told that W, Y and Z are POSITIVE INTEGERS and that W = Y - Z. We're asked if W is a perfect square. This is a YES/NO question.

1) (Y+Z) is a perfect square

IF... Y=7, Z=2 then W = 7-2 = 5 and the answer to the question is NO.
IF... Y=5, Z=4 then W = 5-4 = 1 and the answer to the question is YES.
Fact 1 is INSUFFICIENT

2) Z is even

This tells us NOTHING about Y, but the two TESTs that I used in Fact 1 (above) also 'fit' Fact 2...

IF... Y=7, Z=2 then W = 7-2 = 5 and the answer to the question is NO.
IF... Y=5, Z=4 then W = 5-4 = 1 and the answer to the question is YES.
Fact 2 is INSUFFICIENT

Combined, we already have two TESTs that already fit both Facts, so no new work is needed.
Combined, INSUFFICIENT.

Final Answer: E

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