The population of a community is known to increase at a rate proportional to the number of people present at time t. The initial population P0 has doubled in 5 years. Suppose it is known that the population is 12,000 after 3 years. What was the initial population P0?

Respuesta :

Answer:

P(0) = 7,917

Step-by-step explanation:

The population of the community is given by the following formula:

[tex]P(t) = P(0)(1+r)^{t}[/tex]

In which P(0) is the initial population and r is the growth rate.

The initial population P0 has doubled in 5 years.

This means that

[tex]P(5) = 2P(0)[/tex]

Which lets us find r.

[tex]P(t) = P(0)(1+r)^{t}[/tex]

[tex]2P(0) = P(0)(1+r)^{5}[/tex]

[tex](1+r)^{5} = 2[/tex]

Applying the 5th root to both sides

[tex]1+r = 1.1487[/tex]

[tex]r = 0.1487[/tex]

So

[tex]P(t) = P(0)(1.1487)^{t}[/tex]

Suppose it is known that the population is 12,000 after 3 years.

With this, we find P(0)

[tex]P(t) = P(0)(1.1487)^{t}[/tex]

[tex]12000 = P(0)(1.1487)^{3}[/tex]

[tex]1.5157P(0) = 12000[/tex]

[tex]P(0) = \frac{12000}{1.5157}[/tex]

[tex]P(0) = 7917[/tex]