3. \(1\frac{7}{8}\cdot2\frac{2}{7}\cdot1\frac{2}{5}=\)

\(1\frac{7}{8}=\frac{15}{8}\), \(2\frac{2}{7}=\frac{16}{7}\), \(1\frac{2}{5}=\frac{7}{5}\).

\(\frac{15}{8}\cdot\frac{16}{7}\cdot\frac{7}{5}=\frac{15}{5}\cdot\frac{16}{8}=3\cdot2=6\).

Ответ: 6.