5. Individuals with a concentration of saliva theocyanate exceeding 100 ug/ml are defined to test positive for cigarette smoking, while values less than 100 ug/ml are defined to test negative. The following table shows the joint distribution of smoking status and test results for a population of people with a smoking prevalence of 0.15. Smoking Status Test Result Nonsmokers Smokers Total Negative 0.8245 0.0525 0.877 Positive 0.0255 0.0975 0.123 Total 0.85 0.15 1.0 a. What is the sensivity of the test for smoking? (8 pts.) b. What is the predictive value of a positive test for smoking? (8 pts.)