Specifying the InputStep 2 Rate Equation 
Now, we need to define a formula for the rate Get Sick. Assume that every susceptible person interacts with every infected person once per day. This can be expressed mathematically as Susceptible People * Infected People. Not every interaction results in an infection though, so multiply this total number of interactions by the Infection Fraction to get the number of people who get sick. Procedure:


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