\[\boxed{\text{4.\ 342}}\]
\[\textbf{а)}\ \frac{4}{9} \cdot \left( - \frac{3}{8} \right) = \frac{- 1}{6}\]
\[\textbf{б)} - 2\frac{1}{7} \cdot 1,4 = - \frac{15}{7} \cdot \frac{14}{10} =\]
\[= - \frac{15}{7} \cdot \frac{7}{2} = \frac{- 15}{2}\]
\[\textbf{в)} - 1,3 \cdot \frac{15}{13} = - \frac{13}{10} \cdot \frac{15}{13} = \frac{- 3}{2}\]
\[\textbf{г)} - 1\frac{6}{13} \cdot \frac{1}{19} = - \frac{19}{13} \cdot \frac{1}{19} = \frac{- 1}{13}\]