Problem:
A father takes his twins and a younger child out to dinner on the twins' birthday. The restaurant charges for the father and for each year of a child's age, where age is defined as the age at the most recent birthday. If the bill is , which of the following could be the age of the youngest child?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
The sum of the children's ages is because . If the twins were years old or younger, then the third child would not be the youngest. If the twins are , the youngest child must be .