\[\boxed{\mathbf{55.}}\]
\[\textbf{а)}\ 8,\ 11,\ 3:\]
\[3,\ 8,\ 11.\]
\[Медиана = 8.\]
\[\textbf{б)}\ 7,\ 4,\ 8,\ 1,\ 5:\]
\[1,\ 4,\ 5,\ 7,\ 8.\]
\[Медиана = 5.\]
\[\textbf{в)}\ 10,\ 3,\ 9,\ 8,\ 4,\ 5,\ 7:\]
\[3,\ 4,\ 5,\ 7,\ 8,\ 9,\ 10.\]
\[Медиана = 7.\]