Среднее набора

\(\displaystyle 5{\small ,}\ 6{\small ,}\ 7{\small ,}\ 7{\small ,}\ 9{\small ,}\ 12{\small ,}\ 12{\small ,}\ 14{\small ,}\ 18{\small ,}\ x{\small .}\)

равно \(\displaystyle 11{\small .}\) Найдите \(\displaystyle x{\small .}\)

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