If two events are disjoint (i.e. mutually exclusive) they cannot both occur and so we can determine probabilties by simple addition:
[tex]P(AorB)=P(A)+P(B)[/tex]
[tex]P(AorB)=\frac{40}{61}+\frac{2}{61}[/tex]
[tex]P(AorB)=\frac{42}{61}[/tex]
[tex]P(AorB)\approx 68.8\%[/tex]
A more complete answer would use a joint probability table but that's difficult to type out/format correctly here.
