Assuming a diagnostic test with Sensitivity 80%, Specificity 60%, calculate two positive predictive values, with 21% prevalence and then with 31% prevalence assuming a total number of 4500 people who were screened. Tip: First draw and label TWO 2x2 tables (you will need two tables, one with 21%prevalence and one with 31% prevalence & then calculate positive predictive value from each table). Each table is worth 1 mark each with 0.5 mark for each PPV.