Question

If P(A) = 2/3, P(B) = 1/6, and P(A and B) = 0, what can you say about P(A or B)?

Not sure how to answer this one.

Answer 1

If P(A)∩P(B)=0, then P(A) and P(B) are disjoint, i.e. there is no overlap.

So P(A)∪P(B)=P(A)+P(B)=2/3+1/6=5/6