Three-category prob solving question

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Three-category prob solving question

by jstello » Sat Aug 21, 2010 9:13 am
Can anyone help explain this?

"Half of the students in Metropolis Graduate School's entering class scored over 500 on the GMAT. Of these students, two-thrids were Finance majors. Of the finance majors, three-fifths had worked on Wall Street. What fraction of the entering MBA class were finance majors who scored over 500 on the GMAT but didn't work on Wall Street?"

a. 2/15
b. 1/5
c. 3/10
d. 1/3
e. 2/5

The answer key says it is a. 2/15. i.e. 1/2 * 2/3 * (1-3/5) = 2/15.

(Those who socred over 500) *( of these, the F majors)*(1-the F majors who worked on WS).

I would agree with this if instead of "Of the finance majors, three fifths had worked on WS" it read "Of these finance majors, ..." or something to that effect. Although, I'm not possitive about his. Please help!
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by Dinen » Sat Aug 21, 2010 9:47 am
Hi, I think if you read it slowly and carefully it will make sense. I assume u have no problem with the arithmetic behind the problem, merely the phrasing. Of "these" IMO would imply more than one group of finance majors....however the problem only mentions one group....hence use of the word "the"....as in "the one". Hope this helps.
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by papgust » Sat Aug 21, 2010 7:31 pm
Moving to "Problem Solving" forum!
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by Ian Stewart » Sun Aug 22, 2010 2:09 am
jstello wrote:
I would agree with this if instead of "Of the finance majors, three fifths had worked on WS" it read "Of these finance majors, ..." or something to that effect. Although, I'm not possitive about his. Please help!
You are entirely right. The wording of the question is very bad, though if you replace 'the' with 'these', as you suggest, that would solve the issue. Without that correction, the phrase 'Of the finance majors, three fifths had worked on Wall Street' could very well refer to all of the Finance Majors entering Metro Grad School, and not only those who had scored over 500 on the GMAT. Interpreted that way, the question cannot be answered.

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