[Hi, Bunuel! Let me contribute to this simple but important problem.]

\(? = {m \over w}\,\,\,\,\,\,\,\left( {m,w\,\, \ge 1\,\,{\rm{ints}}} \right)\)

\(\left( 1 \right)\,\,w = {m \over 2} - 3\,\,\,\,\left\{ \matrix{
\,{\rm{Take}}\,\,\left( {m,w} \right) = \left( {8,1} \right)\,\,\,\,\, \Rightarrow \,\,\,\,\,{\rm{?}}\,\,{\rm{ = }}\,\,{\rm{8}}\,\, \hfill \cr
\,{\rm{Take}}\,\,\left( {m,w} \right) = \left( {10,2} \right)\,\,\,\,\, \Rightarrow \,\,\,\,\,{\rm{? }}\,{\rm{ = }}\,\,{\rm{5}}\,\, \hfill \cr} \right.\,\,\,\,\, \Rightarrow \,\,\,\,\,{\rm{INSUFF}}.\)

\(\left( 2 \right)\,\,w = {2 \over 5}m\,\,\,\,\,\mathop \Rightarrow \limits^{w\,\, \ne \,\,0} \,\,\,\,\,{5 \over 2} = {m \over w} = ?\,\,\,\,\,\, \Rightarrow \,\,\,\,\,{\rm{SUFF}}{\rm{.}}\)

The correct answer is therefore (B).

Regards,
Fabio.

P.S.: Bunuel : please take out the typo (extra "2") in the statement (2).
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Just to make sure I'm thinking about this conceptually, This question doesn't even really need math Right?

With W+3 = 1/2M ; M & W can equal anything giving us any ratio.

With W2/5 = M ; This specifically gives us a relationship that is a ratio.

Someone please tell me if I'm off.

Hi MWithrock ,

M and W must be positive integers therefore you don´t have "all freedom" in statement (1).

On the other hand, you are right in statement (2), although W*(5/2)=M, of course. I explain:
Once M/W is unique, the fact that it must be possible to be written as a ratio of positive integers is the examiner´s burden (not yours).

Regards,
Fabio.
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Typo edited. Than you Fabio.
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Statement 1) The number of women enrolled in the class is 3 less than half the number of men enrolled.

w = \(\frac{m}{2} - 3\)

\(\frac{m}{w} = \frac{m}{\frac{m}{2}-3}\)

Clearly INSUFFICIENT.

Statement 2) The number of women enrolled in the class is 2/5 of the number of men enrolled.

w = \(\frac{2}{5}m\)

\(\frac{m}{w} = \frac{m}{\frac{2}{5}m}\)

\(\frac{m}{w} = \frac{5}{2}\)

SUFFICIENT.

OPTION: B

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