Problem:
The average age of people in a room is years. An -year-old person leaves the room. What is the average age of the four remaining people?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Originally the sum of the ages of the people in the room is . After the -year-old leaves, the sum of the ages of the remaining people is . So the average age of the four remaining people is years.
The -year-old is years younger than , so the four remaining people are an average of years older than .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions