In biology, it is often assumed that the number of people that will contract a certain disease is directly proportional to the product of the number of people $y$ who are currently infected with the disease at a particular time $t$ and the number of people $x$ who, at the same time, are not yet infected but who are susceptible to it. Assume that the total population, $P$ , in the study is a constant.(a) What does $\frac { d y } { d t }$ mean?
(b) Determine a differential equation that $y ( t )$ must satisfy.(c) What happens to $y$ as $t \rightarrow \infty$ ?

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The Answer of In biology, it is often assumed that the number of people that will contract a certain disease is directly proportional to the product of the number of people $y$ who are currently infected with the disease at a particular time $t$ and the number of people $x$ who, at the same time, are not yet infected but who are susceptible to it. Assume that the total population, $P$ , in the study is a constant.(a) What does $\frac { d y } { d t }$ mean?
(b) Determine a differential equation that $y ( t )$ must satisfy.(c) What happens to $y$ as $t \rightarrow \infty$ ?

In Biology, It Is Often Assumed That the Number of People