Difference between revisions of "2004 AMC 8 Problems/Problem 9"
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Revision as of 01:02, 12 March 2012
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?
Solution
Let the numbers be
, and
. Thus
and
. Since
,
. Substituting back into our original equation, we have
and
. Dividing by
gives the average of