A fair die is rolled once. Event A is "a 1" and event B is "an even number"…

Step 1. Exclusive? Yes. A $1$ is not even, so the events cannot happen together.

Step 2. Add. $P(A \cup B) = \dfrac{1}{6} + \dfrac{3}{6} = \dfrac{4}{6} \approx 0.6667$.

Step 3. Neither. $1 - \dfrac{4}{6} = \dfrac{2}{6} \approx 0.3333$. These are the rolls $3$ and $5$.