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The mean, median, and unique mode of the positive integers $3,4,5,6,6,7$, and $x$ are all equal. What is the value of $x$ ? (2012 AMC8, Question \#11) 
Overseas Competition->Knowledge Point->Counting Modules->Statistics and Probability->Basic Concepts of Statistics
unique mode: $6$  median: $6$  $(3+4+5+6+6+7+x)\div7=6$  $x=11$ 