(19} In the early stages of an epidemic, almost everybody is Susceptible, and 'i we can treat 5' as a constant. This means that I' is nearly proportional to I , and I grows exponentially. In March 2020, during the rst wave of the Covid-lg pandemic, the number of conrmed cases in the United States rose from 541 on March 8 to 55,500 on March 24. a) if we assume that the number of infected people was growing exponen- tially, on what date did the number of cases hit 5,000? When did the number of cases hit 20,000? b) How long did it take the number of cases to double? c'} It the number of cases continued to grow exponentially, how long would it have taken to reach 50 million cases