For the tree to be useful as a decision-making tool, branch probabilities are required. You are a work-study student in Ms. Taylor's ofce, and since you are taking a statistics course, she asks you to compute the branch probabilities for the decision tree. Let D = the student athlete is a drug user, N = the student athlete is not a drug user, + = the drug test gives a positive result, and the drug test gives a negative result. You decide to conne your analysis to ephedrine use by football players at Green Hill. In a 2005 study of substance use by student athletes conducted by the NCAA, 4.2% of football players reported using ephedrine. You make the assumption that the prevalence of ephedrine use by Green Hill football players is no different from that found in the NCAA study. Based on information provided by the lab that would perform the tests, the test for ephedrine is 95% reliable in both directions: P(+|D) = 0.95, and P(|N) = 0.95