Data Sufficiency

Brent@GMATPrepNow wrote:

Mumbai wrote:Is 1/p > r/(r^2 + 2) ?
a. p = r
b. r > 0
Answer C

Statement 1:
If we replace p with r, the target question becomes "Is 1/r > r/(r^2 + 2)?"
In this form, it might be tough to answer the new target question.
However, since (r^2 + 2) must be positive, we can multiply both sides of the target question by (r^2 + 2) to get a new target question: Is (r^2 + 2)/r > r?
From here, we can simplify the left-hand-side to get Is r + 2/r > r?
Finally, if we subtract r from both sides of the target question, we get Is 2/r > 0?
At this point, it's easy to answer the target question.
2/r can be greater than zero or it can be less than zero.
As such, statement 1 is not sufficient.

Statement 2:
Since we are given no information about p, statement 2 is not sufficient.

Statements 1 AND 2:
Statement 1 allowed us to rewrite the question as Is 2/r > 0?
Since statement 2 tells us that r is positive, we can now answer the new target question with certainty (2/r is definitely greater than zero).

So, the answer is C