Answer 1

\[\text{ Number of red balls } = 3\]
\[\text{ Number of black balls } = 5 \]
\[\text{ Number of white balls } = 4\]
\[\text{ Total number of balls }= 3 + 5 + 4 = 12\]
\[\text{ Therefore, the total number of cases is 12 } . \]

\[P\left( \text{ not a red ball } \right) = 1 - P\left( \text{ a red ball }\right) = 1 - \frac{1}{4} = \frac{3}{4}\]