Suppose that A and B are events defined on a common sample s

Suppose that A and B are events defined on a common sample space and that the following probabilities are known. Find P(A or B). (Give your answer correct to two decimal places.)

P(A) = 0.26, P(B) = 0.36, P(A | B) = 0.22

Solution

By conditional probability rule we have

P(A and B)=P(A|B)P(B)= 0.22 * 0.36=0.0792

Therefore

P(A or B)= P(A)+P(B)-P(A and B)= 0.26+0.36-0.0792=0.5408

So required probability is 0.54.