\[\boxed{\mathbf{58.}}\]
\[\textbf{а)}\ 9,\ 2,\ 8,\ 4:\]
\[2,\ 4,\ 8,\ 9.\]
\[Медиана:\]
\[\frac{4 + 8}{2} = 6.\]
\[\textbf{б)}\ 8,\ 9,\ 5,\ 7,\ 1,\ 3:\]
\[1,\ 3,\ 5,\ 7,\ 8,\ 9.\]
\[Медиана:\]
\[\frac{5 + 7}{2} = 6.\]
\[\textbf{в)}\ 12,\ 11,\ 18,\ 10,\ 22,\ 17,\ 11,\ 14:\]
\[10,\ 11,\ 11,\ 12,\ 14,\ 17,\ 18,\ 22.\]
\[Медиана:\]
\[\frac{12 + 14}{2} = 13.\]