Problem 3 [6 points] In someone infected with measles. the virus level N (measured in number of infected cells per mL of blood plasma) reaches a peak density at about t=12 days (when a rash appears) and then decreases fairly rapidly as a result of immune response. The area under the graph of Mt) from 1': 0 to t=12 (as shown in Figure 2) is equal to the total amount of infection needed to develop symptoms (measured in density of infected cells x time). The function N has been modeled by the function f(t) = t(t 21)(t + 1) Use this model with six subintervals and their midpoints to estimate the total amount of infection needed to develop symptoms of measles. N N = fl!) 1000 0 12 21 rmays) Figure 2