Problem:
A cup of boiling water () is placed to cool in a room whose temperature remains constant at . Suppose the difference between the water temperature and the room temperature is halved every minutes.What is the water temperature, in degrees Fahrenheit, after minutes?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The current difference is . Since we have minutes while halving every minutes, we halve the difference times. This means the difference is multiplied by , so our new difference is . This makes our final temperature .
Thus, the answer is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions