2011 AMC 12A Problem 5

Attempt Problem 5 of the 2011 AMC 12A below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2011 AMC 12A solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

Last summer

30\%

of the birds living on Town Lake were geese,

25\%

were swans,

10\%

were herons, and

35\%

were ducks. What percent of the birds that were not swans were geese?

20

30

40

50

60

The non-swan birds make up

75\%

of the total

Compute

\dfrac{30}{75}

as a percent

The birds that are not swans make up

100\% - 25\% = 75\%

of the total, and geese are

30\%

of the total. The requested fraction is

\dfrac{30}{75} = \dfrac{2}{5} = 40\%.

Thus, the correct answer is C.

Problem 5 in other years