\[\boxed{\text{6.440.}}\]
\[\textbf{а)}\ 5\frac{1}{2} = 5,5\ \]
\[\textbf{б)}\ 6\frac{1}{5} = 6,2\ \]
\[\textbf{в)}\ \ 3\frac{1}{8} = 3,125\]
\[\textbf{г)}\ 1\frac{1}{25} = 1,04\]
\[\textbf{д)}\ 10\frac{1}{50} = 10,02\ \ \ \]