\[\boxed{\text{5.73.}}\]
\[1\ ч = 60\ мин.\ \]
\[\textbf{а)}\ 4\ ч = 4 \cdot 60 = 240\ мин.\]
\[\textbf{б)}\ \frac{1}{3}\ ч = 60\ :3 = 20\ мин.\ \]
\[\textbf{в)}\ 1\ сут = 24\ ч:\]
\[\frac{1}{2}\ сут = 24\ :2 = 12\ ч;\]
\[12\ ч = 12 \cdot 60 = 720\ мин.\ \]
\[\textbf{г)}\ \frac{1}{6}\ ч = 60\ :6 = 10\ мин.\]
\[\textbf{д)}\ \frac{1}{4}\ ч = 60\ :4 = 15\ мин.\ \]
\[\textbf{е)}\ \frac{1}{2}\ ч = 60\ :2 = 30\ мин.\ \ \ \]