At the beginning of 1990​, 21.7 million people lived in the metropolitan area of a particular​ city, and the population was growing exponentially. The 1998 population was 26 million. If this trend​ continues, how large will the population be in the year 2011​?

Respuesta :

Answer:

The population in 2011 will be of 34.88 million people.

Step-by-step explanation:

The population after t years is modeled by an exponential function is the following format:

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

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

At the beginning of 1990​, 21.7 million people lived in the metropolitan area of a particular​ city.

This means that [tex]P(0) = 21.7[/tex]

The 1998 population was 26 million.

1998 is 8 years after 1990. So [tex]P(8) = 26[/tex]

We use this to find the value of r.

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

[tex]26 = 21.7e^{8r}[/tex]

[tex]e^{8r} = \frac{26}{21.7}[/tex]

[tex]\ln{e^{8r}} = \ln{\frac{26}{21.7}}[/tex]

[tex]8r = \ln{\frac{26}{21.7}}[/tex]

[tex]r = \frac{\ln{\frac{26}{21.7}}}{8}[/tex]

[tex]r = 0.0226[/tex]

So

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

[tex]P(t) = 21.7e^{0.0226t}[/tex]

If this trend​ continues, how large will the population be in the year 2011​?

2011 is 21 years after 1990. So this is P(21).

[tex]P(t) = 21.7e^{0.0226t}[/tex]

[tex]P(21) = 21.7e^{0.0226*21}[/tex]

[tex]P(21) = 34.88[/tex]

The population in 2011 will be of 34.88 million people.