S ( t ) denotes numb er of people that is susceptible to the disease but not infected yet.
I ( t ) denotes number of people actually infected.
R ( t ) denotes the numb er of people have recovered.
If we assume
-The fraction of the susceptible who becomes infected per unit time is proportional to the numb er infected, b is the proportional number.
-A ﬁxed fraction rS of the infected population recovers per unit time, 0

Question

S ( t ) denotes numb er of people that is susceptible to the disease but not infected yet.
 I ( t ) denotes number of people actually infected.
R ( t ) denotes the numb er of people have recovered.
If we assume
-The fraction of the susceptible who becomes infected per unit time is proportional to the numb er infected, b is the proportional number.
-A ﬁxed fraction rS of the infected population recovers per unit time, 0 <r <1.
- A ﬁxed fraction of the recovers g become susceptible and infected, 0 < g < 1. proportional function.
· g ·

anonymous · Answer

The system of diﬀerential equations mo del this phenomena are
S' = -bI S + g R
I' = bI S - r I
R' = r I - g R

anonymous · Answer

pleae help me to form it, into a one equation, thanks.,