Just convert it into an equation:

let C = total comimtee members, ans P = population, question is, is P ≤500000
The given data can be transformed to: C = 25+(P-50000)/30000
1) C is know hence can solve P, sufficient!
2)C is given for P = 3P, again can be solved , hence sufficient!

ans = D

anshumaniax wrote:Representation in a local community board is based on the community’s population, with 25 board members representing the first 500,000 people, and each additional board member representing an additional 30,000 people. Is the population of the town less than 500,000?

(1) There were 23 members on the community board.
(2) If the population were three times as large, the community board would have had 51 members.

Is it wrong to assume that within the 'scope of' the question the number 23 doesnt give any relevant information ?
i.e Can i or should i assume if there are n<25 people in the community then only its possible that there are n<25 people on the board.. but in all generality for 500,000 >= n >= 25 there will be 25 board members.

OA is D

What's the source of the question? Whenever you're questioning a question's validity, posting the source is the best way to start.

Statement (1) makes no sense to me at all, which is what makes me immediately discount this question as a valid example of DS.

The original information tells us that there are "25 board members representing the first 500,000 people". Based on that statement, there's no way that it's possible for there to be fewer than 25 members of the board. Statement (1) actually contradicts the original information, which will never happen on the actual GMAT.

Now, if this question did somehow appear on the test and I were forced at gunpoint to answer it, I'd select D, because we know that if there are more than 500000 people there will be more than 25 board members. However, it's definitely a non-GMAT question (unless you haven't perfectly reproduced the prose).

Thanks Stuart. That Q is from a Princeton Review mock test. Aaaargh. Just got that in mine.