The number N(t) of people in a community who are exposed to a particular advertisement is governed by the logistic equation. Initially, N(0) = 500, and it is observed that N(1) = 1000. Solve for N(t) if it is predicted that the limiting number of people in the community who will see the advertisement is 50,000.

Respuesta :

Answer:

[tex]N(x)=\frac{50000}{1+99e^{\ln(\frac{49}{99})x}}[/tex]

Step-by-step explanation:

The logistic equation is

[tex]N(x)=\frac{c}{1+ae^{-rx}}[/tex]

where:

c/(1+a) is the initial value.

c is the limiting value

r is constant determined by growth rate

So we are given that:

N(0)=500 or that c/(1+a)=500

If your not sure about his initial value of c/(1+a) then replace x with 0 in the function N:

[tex]N(0)=\frac{c}{1+ae^{-r \cdot 0}}[/tex]

Simplify:

[tex]N(0)=\frac{c}{1+ae^{0}}[/tex]

[tex]N(0)=\frac{c}{1+a(1)}[/tex]

[tex]N(0)=\frac{c}{1+a}[/tex]

Anyways we are given:

[tex]\frac{c}{1+a}=500[/tex].

Cross multiplying gives you [tex]c=500(1+a)[/tex].

We are also giving that N(1)=1000 so plug this in:

[tex]N(1)=\frac{c}{1+ae^{-r \cdot 1}}[/tex]

Simplify:

[tex]N(1)=\frac{c}{1+ae^{-r}}[/tex]

So this means

[tex]1000=\frac{c}{1+ae^{-r}}[/tex]

Cross multiplying gives you [tex]c=1000(1+ae^{-r})[/tex]

We are giving that c=50000 so we have these two equations to solve:

[tex]50000=500(1+a)[/tex]

and

[tex]50000=1000(1+ae^{-r})[/tex]

I'm going to solve [tex]50000=500(1+a)[/tex] first because there is only one constant variable here,[tex]a[/tex].

[tex]50000=500(1+a)[/tex]

Divide both sides by 500:

[tex]100=1+a[/tex]

Subtract 1 on both sides:

[tex]99=a[/tex]

Now since we have [tex]a[/tex] we can find [tex]r[/tex] in the second equation:

[tex]50000=1000(1+ae^{-r})[/tex] with [tex]a=99[/tex]

[tex]50000=1000(1+99e^{-r})[/tex]

Divide both sides by 1000

[tex]50=1+99e^{-r}[/tex]

Subtract 1 on both sides:

[tex]49=99e^{-r}[/tex]

Divide both sides by 99:

[tex]\frac{49}{99}=e^{-r}[/tex]

Take natural log of both sides:

[tex]\ln(\frac{49}{99})=-r[/tex]

Multiply both sides by -1:

[tex]-\ln(\frac{49}{99})=r[/tex]

So the function N with all the write values plugged into the constant variables is:

[tex]N(x)=\frac{50000}{1+99e^{\ln(\frac{49}{99})x}}[/tex]