A certain virus infects one in every 600 people A test used to detect the virus in a person is positive 90 of the time if the person has the virus and 10 of the time if the person does not have the virus Let A be the event the person is infected and B be the event the person tests positive a Find the probability that a person has the virus given that they have tested positive b Find the probability that a person does not have the virus given that they have tested negative