Problem:
Sarah pours four ounces of coffee into an eight-ounce cup and four ounces of cream into a second cup of the same size. She then transfers half the coffee from the first cup to the second and, after stirring thoroughly, transfers half the liquid in the second cup back to the first. What fraction of the liquid in the first cup is now cream?
Answer Choices:
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Solution:
After the first transfer, the first cup contains two ounces of coffee, and the second cup contains two ounces of coffee and four ounces of cream. After the second transfer, the first cup contains ounces of coffee and ounces of cream. Therefore, the fraction of the liquid in the first cup that is cream is .
The problems on this page are the property of the MAA's American Mathematics Competitions