Art of Problem Solving

2010 AMC 8 Problems/Problem 12: Difference between revisions

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==See Also==
==See Also==
{{AMC8 box|year=2010|num-b=11|num-a=13}}
{{AMC8 box|year=2010|num-b=11|num-a=13}}
{{MAA Notice}}

Revision as of 00:50, 5 July 2013

Problem

Of the $500$ balls in a large bag, $80%$ (Error compiling LaTeX. Unknown error_msg) are red and the rest are blue. How many of the red balls must be removed so that $75%$ (Error compiling LaTeX. Unknown error_msg) of the remaining balls are red? $\textbf{(A)}\ 25\qquad\textbf{(B)}\ 50\qquad\textbf{(C)}\ 75\qquad\textbf{(D)}\ 100\qquad\textbf{(E)}\ 150$

Solution

Since 80 percent of the 500 balls are red, there are 400 red balls. Therefore, there must be 100 blue balls. For the 100 blue balls to be 25% or $\dfrac{1}{4}$ of the bag, there must be 400 balls in the bag so 100 red balls must be removed. The answer is $\boxed{\textbf{(D)}\ 100}$.

See Also

2010 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 11
Followed by
Problem 13
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AJHSME/AMC 8 Problems and Solutions

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