\[1)\ P(A) = \frac{3}{(4 - 1) + 3} = \frac{3}{6} = \frac{1}{2};\]
\[2)\ P(A) = \frac{4 - 1}{(4 - 1) + 3} = \frac{3}{6} = \frac{1}{2};\]
\[3)\ P(A) = \frac{4}{4 + (3 - 1)} = \frac{4}{6} = \frac{2}{3};\]
\[4)\ P(A) = \frac{3 - 1}{4 + (3 - 1)} = \frac{2}{6} = \frac{1}{3}.\]