The town of Pinedale, Wyoming, is experiencing a population boom. In 1990, the population was 860 and five years later it was 1210. (a) Find a linear model l(x) and an exponential model p(x) for the population of Pinedale in the year 1990+x. (b) What do these models estimate the population of Pinedale to be in the year 2000?

Respuesta :

Answer:

a) [tex] m = \frac{1210-860}{5-0} =70[/tex]

Now we can find the intercept using the first condition:

[tex] 860 = 70*0 +b[/tex]

[tex] b =860[/tex]

And the model would be given by:

[tex] y = 70 x +860[/tex]

[tex] y= A e^{rt}[/tex]

The initial amount is A = 860 and we have:

[tex] y = 860 e^{rt}[/tex]

Now we can use the second condition:

[tex] 1210= 860 e^{5r}[/tex]

And solving for r we got:

[tex] \frac{121}{86} = e^{5r}[/tex]

[tex]r= 0.0682886[/tex]

And the model would be:

[tex] y = 860 e^{0.0682886 t}[/tex]

b) [tex] y = 70*10 +860=1560[/tex]

Step-by-step explanation:

Part a

For this case we have the following info given:

[tex] x_1 = 0 , y_1 = 860[/tex]

Where 0 represent the starting year in 1990.

And 5 years later we have 1210 people:

[tex] x_2 = 5, y_2 = 1210[/tex]

And we want to create a model like this:

[tex] y = mx +b[/tex]

And we can estimate the slope like this:

[tex] m= \frac{y_2 -y_1}{x_2 -x_1}[/tex]

And replacing we got:

[tex] m = \frac{1210-860}{5-0} =70[/tex]

Now we can find the intercept using the first condition:

[tex] 860 = 70*0 +b[/tex]

[tex] b =860[/tex]

And the model would be given by:

[tex] y = 70 x +860[/tex]

And if we want an exponential model like this:

[tex] y= A e^{rt}[/tex]

The initial amount is A = 860 and we have:

[tex] y = 860 e^{rt}[/tex]

Now we can use the second condition:

[tex] 1210= 860 e^{5r}[/tex]

And solving for r we got:

[tex] \frac{121}{86} = e^{5r}[/tex]

[tex]r= 0.0682886[/tex]

And the model would be:

[tex] y = 860 e^{0.0682886 t}[/tex]

Part b

For this case we want to estimate the population in the year 2000. And that represent 10 years from 1990 so then x =10 and replacing we got:

[tex] y = 70*10 +860=1560[/tex]

And for the exponential model we have:

[tex] y = 860 e^{0.0682886*10} =1702.441[/tex]

The linear model estimates the population to be 1560, while the exponential model estimates the population to be 1692 in 2000.

x represents the number of years after 1990

So, the given parameters are:

[tex]\mathbf{(x,y) = (0,860)\ (5,1210)}[/tex]

(a) The linear and exponential functions

The linear function

Start by calculating the slope (m)

[tex]\mathbf{m = \frac{y_2 - y_1}{x_2 - x_1}}[/tex]

So, we have:

[tex]\mathbf{m = \frac{1210 - 860}{5-0}}[/tex]

[tex]\mathbf{m = \frac{350}{5}}[/tex]

[tex]\mathbf{m = 70}[/tex]

So, the linear function is:

[tex]\mathbf{l(x) = m(x - x_1) + y_1}[/tex]

This gives

[tex]\mathbf{l(x) = 70(x - 0) + 860}[/tex]

[tex]\mathbf{l(x) = 70x + 860}[/tex]

The exponential function

An exponential function is represented as:

[tex]\mathbf{y = ab^x}[/tex]

When x  = 0, we have:

[tex]\mathbf{860 = ab^0}[/tex]

[tex]\mathbf{860 = a}[/tex]

So, we have:

[tex]\mathbf{a = 860 }[/tex]

When x = 5, we have:

[tex]\mathbf{1210 = ab^5}[/tex]

Substitute [tex]\mathbf{a = 860 }[/tex]

[tex]\mathbf{1210 = 860b^5}[/tex]

Divide both sides by 860

[tex]\mathbf{1.40697674419 = b^5}[/tex]

Take 5th roots of both sides

[tex]\mathbf{1.07067431388 = b}[/tex]

Rewrite as:

[tex]\mathbf{b = 1.07067431388 }[/tex]

Approximate

[tex]\mathbf{b = 1.07}[/tex]

So, the exponential model is:

[tex]\mathbf{p(x) = 860 \times 1.07^x}[/tex]

(b) The value of the models in the year 2000

Here, x = 10

So, we have:

[tex]\mathbf{l(x) = 70x + 860}[/tex]

[tex]\mathbf{l(10) = 70 \times 10 + 860}[/tex]

[tex]\mathbf{l(10) = 1560}[/tex]

Similarly,

[tex]\mathbf{p(x) = 860 \times 1.07^x}[/tex]

[tex]\mathbf{p(10) = 860 \times 1.07^{10}}[/tex]

[tex]\mathbf{p(10) = 1692}[/tex]

Hence, the linear model estimates the population to be 1560, while the exponential model estimates the population to be 1692 in 2000.

Read more about population models at:

https://brainly.com/question/24172878