11) \(\frac{14}{55}\cdot1\frac{1}{21}\)

\(1\frac{1}{21}=\frac{22}{21}\).

\[\frac{14}{55}\cdot\frac{22}{21}=\frac{2\cdot22}{55\cdot3}=\frac{44}{165}=\frac{4}{15}.\]

Ответ: \(\frac{4}{15}\).