\[\boxed{\mathbf{2.2}\mathbf{67}}\]
Пояснение.
Решение.
\[\textbf{а)}\ \frac{3}{4}\ ч \cdot 2 = \frac{3 \cdot 2}{4}\ \ ч = \frac{3}{2}\ ч =\]
\[= 1\frac{1}{2}\ ч.\]
\[\textbf{б)}\ \frac{9}{12}\ ч \cdot 4 = \frac{9 \cdot 4}{12}\ ч = \frac{9}{3}\ ч =\]
\[= 3\ ч.\]
\[\textbf{в)}\ \frac{7}{15}\ ч \cdot 15 = \frac{7 \cdot 15}{15}\ ч = 7\ ч.\]
\[\textbf{г)}\ \frac{11}{15}\ ч \cdot 7 = \frac{11 \cdot 7}{15}\ \ ч = \frac{77}{15}\ ч =\]
\[= 5\frac{2}{15}\ ч.\]