Problem:
The average of the five numbers in a list is . The average of the first two numbers is . What is the average of the last three numbers?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The sum of all five numbers is . The sum of the first two numbers is , so the sum of the last three numbers is . The average of the last three numbers is .
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions