The population of a town grows at a rate proportional to the population present at time t. The initial population of 500 increases by 25% in 10 years. What will be the population in 20 years

Respuesta :

Answer:

The population in 20 years will be 781.

Step-by-step explanation:

The population of the town can be modeled by the following equation:

[tex]P(t) = P(0)e^{rt}[/tex]

In which P(t) is the population after t years, P(0) is the initial population and r is the growth rate, as a decimal.

The initial population of 500 increases by 25% in 10 years.

This means that [tex]P(0) = 500, P(10) = 1.25*P(0) = 625[/tex]

We use this to find r.

[tex]P(t) = P(0)e^{rt}[/tex]

[tex]625 = 500e^{10r}[/tex]

[tex]e^{10r} = 1.25[/tex]

Applying ln to both sides

[tex]\ln{e^{10r}} = \ln{1.25}[/tex]

[tex]10r = \ln{1.25}[/tex]

[tex]r = \frac{\ln{1.25}}{10}[/tex]

[tex]r = 0.0223[/tex]

So

[tex]P(t) = 500e^{0.0223t}[/tex]

What will be the population in 20 years

This is P(20)

[tex]P(20) = 500e^{0.0223*20} = 781[/tex]

The population in 20 years will be 781.