A disease with classes S, I and Ris represented by the following system of differential equations ds = -BSI + yR, dt dI = BS I - ul, dt (4) %3D dR = ul - yR, dt where B, y and are positive parameters. (iv) Suppose the vaccination program vaccinates a proportion p of the population before it can catch the disease. What percentage of the population in a town of size N = 100000 must be vaccinated to eradicate the disease if = 0.001, H = 10 and y = 5? [2 marks]