Question

Find P(A or B), if the events are disjointed.

P(A) = 9/25
P(B) = 9/25

Answer 1

since the two events are disjoint, just add them up

Answer 2

\[P(A\cup B)=P(A)+P(B)-P(A\cap B)\]
As mentioned above, \(A\cap B=\emptyset\), so \(P(A\cap B)=0\).