According to the SI model of disease discussed in class, the number of individuals I infected by a disease changes in time t according to the logistic equation dI = rI (1-7), dt where r > 0 is the initial growth rate of the infected population and N> 0 is the total population (assumed to be constant, i.e., no dying). The number of individuals susceptible to the disease S can be determined according to S = N - I. a. Assume the initial infected population is Io. Determine a formula for the infected population as a function of time t. b. Suppose Io