Data Sufficiency

crackgmat007 wrote:3. If k, m, and p are integers, is k � m � p odd?
(1) k and m are even and p is odd.
(2) k, m, and p are consecutive integers.

The answer seems to be A, but why is statement 2 not sufficient?

k - m - p = k - (m + p)

(1) m is even and p is odd.
So m + p is odd.
k is even.
So k - (m + p) is odd; SUFFICIENT.

(2) Since k, m and p are consecutive integers, let m = k + 1 and p = k + 2.
So m + p is 2k + 3.
k - (m + p) is k - (2k + 3) = -k - 3.
So the value of k - (m + p) depends on whether k is even or odd; NOT sufficient.

The correct answer is A.

crackgmat007 wrote:3. If k, m, and p are integers, is k - m - p odd?
(1) k and m are even and p is odd.
(2) k, m, and p are consecutive integers.

The answer seems to be A, but why is statement 2 not sufficient?

Target question: Is k - m - p odd?

To show why statement 2 is not sufficient, we can plug in some values for k, m and p that satisfy the given condition that k, m, and p are consecutive integers. Here are 2 possible cases:
case a: k=2, m=3, p=4, in which case k-m-p= -5 (so k-m-p is odd)
case b: k=1, m=2, p=3, in which case k-m-p= -4 (so k-m-p is not odd)
Since we get conflicting answers to the target question, statement 2 is NOT SUFFICIENT.

Cheers,
Brent

TRiXcare wrote:Analogues are available?

I'm not sure about external sites, but you can use BTG's tagging feature to examine tons of other GMAT questions that test Integer Properties: https://www.beatthegmat.com/forums/tags/ ... roperties

Cheers,
Brent