If P(A) = 0.3, P(B) = 0.8, and P(A or B) = 0.9, find P(A and B).

Question

Addition & Complement Rule

Answer 1

In general, P(A or B)=P(A)+P(B)-P(A and B). With this, you can answer your question with the information given. In the equation above, you are given P(A or B), P(A), and P(B). With a little algebra, you can arrive at the value of P(A and B).