\[\boxed{\mathbf{269.}}\]
\[\textbf{а)}\ На\ 3\ делится\ 3\ и\ 6:\]
\[\frac{2}{6} = \frac{1}{3}.\]
\[ES = n \cdot p = 120 \cdot \frac{1}{3} = 40.\]
\[\textbf{б)}\ ES = 120 \cdot \frac{1}{6} = 20.\]