Acertain virus infects one in every 200 people. a test used to detect the virus in a person is positive 70% of the time when the person has the virus and 5% of the time when the person does not have the virus. (this 5% result is called a false positive.) let a be the event "the person is infected" and b be the event "the person tests positive." (a) using bayes' theorem, when a person tests positive, determine the probability that the person is infected. (b) using bayes' theorem, when a person tests negative, determine the probability that the person is not infected.