Bunuel wrote:

At a public housing conference 15 percent of the attendees are male. After the speaker finishes, several female attendees but no males leave the conference and the total number of persons remaining is 60 percent of the original number. The number of female attendees who leave is what fraction of the original number of females attending the conference?

(A) 11/20

(B) 9/17

(C) 8/17

(D) 9/20

(E) 2/5

We can let 100 be the number of attendees originally at the conference. Thus, there are 15 males and 85 females. If only females have left and no males have left, and the total number of people remaining is 60, it must mean that 40 females have left. Therefore, the number of female attendees who have left is 40/85 = 8/17 of the original number of female attendees at the conference.

Alternate Solution:

Let’s let n = the original total number of attendees. Thus, 0.15n = the number of male attendees and 0.85 = the number of female attendees. Now, let’s let x = the number of females who leave. We have:

n - x = 0.6n

0.4n = x

We know that 0.4n is the number of females who left. Thus, the percentage of females who left, out of the total number of females who originally attended, is (0.4n)/(0.85n) = 40/85 = 8/17.

Answer: C

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