\[\boxed{\text{5.146.}}\]
\[1\ т = 1\ 000\ кг.\]
\[\frac{1}{2}\ т = 1\ 000\ :2 = 500\ кг;\ \]
\[\frac{1}{4}\ т = 1\ 000\ :4 = 250\ кг;\ \]
\[\frac{1}{3}\ т = 1\ 000\ :3 \approx 333\ кг;\ \]
\[\frac{1}{20}\ т = 1\ 000\ :20 = 50\ кг.\ \ \]