\[P = 1 - P_{3}(3) =\]
\[= 1 - C_{3}^{3} \bullet \left( \frac{1}{2} \right)^{3} \bullet \left( 1 - \frac{1}{2} \right)^{3 - 3} =\]
\[= 1 - 1 \bullet \frac{1}{2^{3}} \bullet \left( \frac{1}{2} \right)^{0} = 1 - \frac{1}{8} = \frac{7}{8}.\]
\[Ответ:\ \ \frac{7}{8}.\]