Problem Solving

The ratio of the volumes of two empty pools is 5 : 3. If the smaller pool is filled and emptied into the larger pool, what is the ratio of filled volume to empty volume in the pools?
(A) 1 : 4
(B) 2 : 5
(C) 3 : 5
(D) 3 : 8
(E) 5 : 8

OA: D

Is this a typical GMAT question? I am not certain of the source's authenticity

neeti2711 wrote:The ratio of the volumes of two empty pools is 5 : 3. If the smaller pool is filled and emptied into the larger pool, what is the ratio of filled volume to empty volume in the pools?
(A) 1 : 4
(B) 2 : 5
(C) 3 : 5
(D) 3 : 8
(E) 5 : 8

OA: D

Is this a typical GMAT question? I am not certain of the source's authenticity

An official question would have to be far more clearly worded than this one. Say we started with the initial scenario

Large empty pool capacity: 5x
Small empty pool capacity: 3x
Total empty pool capacity: 8x

Well, if you fill the small pool, there will be 3x units of water in the small pool and no water in the large pool. If you emptied that 3x into the larger pool, now you'd have 3x of the 5x of that large pool filled, (and 2x excess capacity) along with an empty small pool. So what is this question asking for? Do they want the ratio of water currently in the large pool to the previously empty total capacity of both pools? (This would give you a ratio of 3x/8x or 3/8.) Do they want the ratio of the currently filled portion of the large pool to the currently unfilled portions of both pools? (If there's 2x excess capacity in the large pool and 3x in the empty small pool, this would give you a ratio of 3x/(2x + 3x) = 3x/5x = 3/5.) Why would it matter that we've transferred the water from the small pool to the large if the question is asking about the total water amount of both pools? Unless there's something I'm missing here, I'd ignore this one.

Thank you David, Rich and Jay!

I agree with David that the question is a bit ambiguous. I chose C as the answer. I still feel that to get 3:8 as the answer, the question should be differently worded. I guess the source isn't reliable.

My guess was that our author, Humpty Dumpty, meant "filled volume" to signify the amount of water in both pools combined and "empty volume" to signify the remaining space in both pools combined ... but then that wasn't the answer, even though it was an answer choice! Yuck. (Maybe I'm neglecting "unfilled volume", with the equation "unfilled volume" + "filled volume" = "empty volume"? What on earth is going on here?)

Ceilidh,

The source of the above question is bellcurves.com. I read about this source on the experience shared by an 800 scorer on this website. I started solving the questions, but these questions were not as perfect as OG questions and the answer explanations were vague.

Thank you for your help! Now I have stopped visiting this site.