If the drama club and music club is combined, what percent of the comb

No C is not right. We cannot assume that there is no overlap between the clubs.

If the drama club and music club is combined, what percent of the combined membership is male?

(1) Of the 16 members of the drama club, 15 are male. Not sufficient.

(2) Of the 20 members of the music club, 10 are male. Not sufficient.

(1)+(2) Since we don't know how many members of the drama club were also the members of the music club then we can not assume that there wasn't any overlap between the clubs and simply write (15+10)/(16+20), so even taken together statements are not sufficient.

Answer: E.
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One important takeaway here is that questions in GMAT are NEVER that easy, I guess unless you are doing extremely bad in the exam but even then. Always think twice before answering something that seems really easy or "obvious"

1) 15 are male and 1 female in Drama club. Tells nothing about music club. Not sufficient.
2) 10 are male and 10 female in Music club. Tells nothing about drama club. Not sufficient.

Combining both;

25 Males out of 36 members; % of male found.
Sufficient.

Ans: "C"

Hi All,

DS questions are built to test a variety of skills besides 'math skills', including organization, accuracy, thoroughness, attention-to-detail, ability to see that there is more than one possible answer and the ability to prove that you're correct (when dealing with limited information).

While this prompt looks (and is) relatively simple, it does test the thoroughness of your thinking....



It's important to consider what the answer to any given DS question could be. In many cases, there is more than just the 'obvious' solution.

GMAT assassins aren't born, they're made,
Rich
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So you are telling when we encounter such question we should assume overlap even without it explicityly mentioning it?? it is pretty confusing that way.

It's the other way around: we cannot assume that there is no overlap between the clubs.
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We don't know the overlap, i.e the number of folks in the drama club, who are also members of the music club and vice versa.
Take this example,
20 members of the music club - 10 are male
all those 10 are also part of the drama club,
total ## of unique members: (16+ 20) - 10 = 26
## of males = 15
so % of males : 15/26 * 100

what if all members were exclusive, ie. no overlap
then % of males : 25/26 * 100

Therefore: E
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\(? = {{\# \,{\rm{drama}}\,{\rm{males}}\,\,\, + \,\,\,\# \,{\rm{music}}\,{\rm{males}}\,\,\, - \,\,\,\# \left( {\,{\rm{drama}}\,{\rm{and}}\,{\rm{music}}\,\,\,{\rm{males}}} \right)} \over {\# \,{\rm{drama}}\,\,\, + \,\,\,\# \,{\rm{music}}\,\,\, - \,\,\,\# \left( {\,{\rm{drama}}\,{\rm{and}}\,{\rm{music}}} \right)}}\)


\(\left( {1 + 2} \right)\,\,\left\{ \matrix{\\
\,\# \,{\rm{drama}}\,\, = \,\,16\,\,\,\,,\,\,\,\,\# \,\,{\rm{drama}}\,{\rm{males}}\,\,{\rm{ = 15}} \hfill \cr \\
\,\# \,{\rm{music}}\,\,{\rm{ = }}\,\,{\rm{20}}\,\,\,\,,\,\,\,\,\# \,\,{\rm{music}}\,{\rm{males}}\,\,{\rm{ = 10}} \hfill \cr} \right.\)


\(? = {{15\,\, + \,\,10\,\, - \,\,\# \left( {\,{\rm{drama}}\,{\rm{and}}\,{\rm{music}}\,\,\,{\rm{males}}} \right)} \over {16\,\, + \,\,20\,\, - \,\,\# \left( {\,{\rm{drama}}\,{\rm{and}}\,{\rm{music}}} \right)}}\)


Now I believe the (1+2) bifurcation viability is trivially seen, hence the answer is (E), indeed.


We follow the notations and rationale taught in the GMATH method.

Regards,
Fabio.
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I don't get it. Why do we have to assume there is going to be an overlap or "Both" Value? I understand that GMAT questions can get tricky but the type of language used is very subjective to me.

Hi RastogiSarthak99,

DS questions are built to test a variety of skills besides 'math skills', including organization, accuracy, thoroughness, attention-to-detail, ability to see that there is more than one possible answer and the ability to prove that you're correct (when dealing with limited information).

It often helps to be a little 'cynical' with the information that DS question gives you. For example, if a prompt told you that X is an INTEGER.... does that mean that X must be positive? Couldn't X be 0 or negative?

In this question, we're told to combine the membership of 2 clubs..... does that mean that nobody could be in BOTH clubs already? There might be some 'overlap' or there might be 'no overlap' so we have to be thorough and consider the possibilities. Solving for the correct answer depends on YOUR ability to be thorough with your thinking - and that's a skill that ALL Business Schools really want in their students.

GMAT assassins aren't born, they're made,
Rich
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Is there anyone here who would be able to graphically represent this problem? In terms of Venn diagram

This is tricky question and emphasize on wording of question and not on calcuation

Sentence-1 Not Sufficient

Sentence-2 Not Sufficient

Both Sentence 1 & 2 Not Sufficient (No data of combined membership)

IMO E
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My 2 cents on this:

It is so easy to choose C. but whenever it's that easy, I usually have to rethink. It's never THAT easy. Okay, now let's go:

1. Drama = 16, Males = 15; Music? Insuff
2. Music = 20; Male = 10; Drama? Insuff

Combine 1 and 2:

Drama + Music = 36; Males = 10 + 15 = 25. CASE: NO OVERLAP

Drama + Music = 20; Males = 15. CASE = IF THERE IS OVERLAP

Two different cases, hence E.

Very tricky my friends! Bunuel - know of any similar questions?