The graphs on pages 3 and 4 have no scales marked along their axes, so they provide only qualitative information. The graphs below do have scales, so you can now answer quantitative questions about them. For example, on day 20 there are about 18,000 susceptible people. Read the graphs to answer the following questions. (Note: S + I + R is not constant in this example, so these graphs cannot be solutions to our model..)
R as accurately as you can, and then
superimpose a sketch of S on it. Notice the time scales on the
original graphs of S and R are different. Describe what
happened to the graph of S when you superimposed it on the graph of
R. Did it get compressed or stretched? Was this change in the
horizontal direction or the vertical?