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2011 AMC 10A Problem 8

Problem 8 of 25EasierAlgebra

Last summer 30%30 \% of the birds living on Town Lake were geese, 25%25 \% were swans, 10%10 \% were herons, and 35%35 \% were ducks. What percent of the birds that were not swans were geese?

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Solution

WLOG, let there be 100100 birds. Then 7575 birds are not swans. The desired percentage is then 3075⋅100=40%. \dfrac{30}{75} \cdot 100 = 40 \%. Thus, C is the correct answer.

More practice

Concepts: percentage · ratio and proportion

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