1.Define and give formulas for attack rate, secondary attack rate, and case fatality rate.

2. A flu outbreak occurred in a university dorm that housed 20 students. Case A began on October 1 and case B was diagnosed on October 2. After about 10 days, 12 additional cases occurred during about a one-week time span. School epidemiologists believed that this second group of cases represented the same generation of cases, and was in the second incubation period after the occurrence of cases A and B; none of the 20 students was known to be immune. Calculate the secondary attack? Show your work.