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2008 AIME I Problems/Problem 1

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Problem

Of the students attending a school party, 60\% of the students are girls, and 40\% of the students like to dance. After these students are joined by 20 more boy students, all of whom like to dance, the party is now 58\% girls. How many students now at the party like to dance?

Solution

Say that there were 3k girls and 2k boys at the party originally. 2k like to dance. Then, there are 3k girls and 2k + 20 boys, and 2k + 20 like to dance.

Thus, \dfrac{3k}{5k + 20} = \dfrac{29}{50}, solving gives k = 116. Thus, the number of people that like to dance is 2k + 20 = \boxed{252}.

See also

2008 AIME I (ProblemsResources)
Preceded by
First Question
Followed by
Problem 2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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