Answer:
Given function is:
[tex]f(t)=\frac{200000}{1+2000e^{-t}}[/tex]
Part A:
When t = 0
[tex]f(0)=\frac{200000}{1+2000e^{-0}}[/tex]
= [tex]\frac{200000}{1+2000e^{-0}}[/tex]
= [tex]\frac{200000}{1+2000}[/tex]
= [tex]\frac{200000}{2001}[/tex]
= 99.95 rounding to 100 people.
Part B:
[tex]f(4)=\frac{200000}{1+2000e^{-4}}[/tex]
= [tex]\frac{200000}{1+2000(0.0183156)}[/tex]
= [tex]\frac{200000}{1+36.6312}[/tex]
= [tex]\frac{200000}{37.6312}[/tex]
= 5314.73
So, approximately 5,315 people were ill by the end of the 4th week.
Part C:
Let 't' be approaching infinity.
[tex]e^{-t}[/tex] will approach zero, so f(infinity)=[tex]\frac{200000}{1+0}[/tex]
f(infinity)=200000
Hence, the limit is that all of the persons can become ill.