On January 1, 2000 there were 20 Tufts medical students with Influenza A and there was a total of 600 students in the class. These 20 students were immune from contracting Influenza A again during the next nine months. From January 2, 2000 through April 2, 2000, 30 more students developed Influenza A and the class size remained at 600.
What was the cumulative incidence of Influenza A from January 2, 2000 through April 2, 2000? (Show your work.)
What was the prevalence of Influenza A on January 1, 2000?