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 initial temperature difference is degrees, so during the first minutes the difference decreases by half to degrees. The next minutes reduces the difference by half again to degrees, and another minutes shrinks the difference to degrees. Thus after minutes the water temperature has dropped to degrees Fahrenheit.
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions