\[\boxed{\mathbf{218.}}\]
\[\textbf{а)}\ P = p \cdot q^{3} =\]
\[= 0,2 \cdot {0,8}^{3} = 0,1024.\]
\[\textbf{б)}\ P = 1 - q^{3} = 1 - {0,8}^{3} =\]
\[= 0,488.\]