2011 AMC 12A Problems/Problem 5

Problem

Last summer $30%$ (Error compiling LaTeX. Unknown error_msg) of the birds living on Town Lake were geese, $25%$ (Error compiling LaTeX. Unknown error_msg) were swans, $10%$ (Error compiling LaTeX. Unknown error_msg) were herons, and $35%$ (Error compiling LaTeX. Unknown error_msg) were ducks. What percent of the birds that were not swans were geese?

$\textbf{(A)}\ 20 \qquad \textbf{(B)}\ 30 \qquad \textbf{(C)}\ 40 \qquad \textbf{(D)}\ 50 \qquad \textbf{(E)}\ 60$

Solution

To simplify the problem, let us say that there were a total of 100 birds. The number of birds that are not swans is 75. The number of geese is 30. Therefore the percentage is just $\frac{30}{75} \times 100 = 40 \Rightarrow \boxed{C}$

2011 AMC 12A (Problems • Answer Key • Resources)
Preceded by Problem 4	Followed by Problem 6
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2011 AMC 12A Problems/Problem 5

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