1 Consider an infectious disease of SIR type with an average pe- riod of infectiousness of 7 days; assume that each individual contacts on average 3 different people per day, and that there is 10% probability that a susceptible, contacted by an infected. becomes infection. Assume that the initial population is 1.4 millions of susceptibles, that the initial number of infectives be extremely low, and that births and deaths can be neglected. (a) Determine the basic reproductive number Ro. (b) Determine the number of infectives at the peak. (c) Determine the fraction of the population that should be vaccinated at the start of the epidemic to prevent its spread. (d) Approximate as well as you can the number of susceptibles at the end of the epidemic.