Problem:
At an elementary school, the students in third grade, fourth grade, and fifth grade run an average of 12,15 , and 10 minutes per day, respectively. There are twice as many third graders as fourth graders, and twice as many fourth graders as fifth graders. What is the average number of minutes run per day by these students?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Let equal the number of fifth graders. Then there are fourth graders and third graders. The total number of minutes run per day by the students is . There are a total of students, so the average number of minutes run by the students per day is .
The problems on this page are the property of the MAA's American Mathematics Competitions