In this problem, we have the following equation:
![\hat{y}=P(x)=38,257-0.1629\cdot x.](https://img.qammunity.org/2023/formulas/mathematics/college/e42u77z6bksxgqk06vy6rjg935o0zom8n4.png)
$$\hat{y}=P(x)=38,257-0.1629\cdot x.$$Where:
• y^ = P(x) = Price of x miles driven by a Ford F-150's,
,
• x = # of miles driven by a Ford F-150's.
a) For x = 100,000, we get:
![P(100,000)=21,967.](https://img.qammunity.org/2023/formulas/mathematics/college/1ymjpeaicg7m26ezqlmi9eea8cjs12qmo8.png)
b) The general equation of a line is:
![y=b+m\cdot x\text{.}](https://img.qammunity.org/2023/formulas/mathematics/college/63dicspq04200t04lw8ct4xri2l3u5e57s.png)
Where:
• b = y-intercept,
,
• m = slope.
Comparing the general equation with the equation of the problem, we have:
![m=-0.1629.](https://img.qammunity.org/2023/formulas/mathematics/college/zxhxbdjnt2yqa8ej6f4ofuwf6hpfys6sne.png)
Because the dependent and the independent variables are:
• y = Price of x miles driven by a Ford F-150's,
,
• x = # of miles driven by a Ford F-150's.
The slope m with its units is:
![m=-0.1629\cdot\frac{\text{units of price}}{\text{miles driven}}\text{.}](https://img.qammunity.org/2023/formulas/mathematics/college/o8g4k06v5g27w7yewx580f1bejf2u4j9xm.png)
c) Comparing the equation of the problem and the general equation of a line, we find the value of the y-intercept:
![b=38,257.](https://img.qammunity.org/2023/formulas/mathematics/college/8sife1wuzu7olgwicix33jit907suy12jf.png)
The value of the y-intercept is the value of y when we have x = 0, i.e. when we have driven 0 miles. The units of the y-intercept are the same as the variable y, so the y-intercept with units is:
![b=38,257\text{ units of price.}](https://img.qammunity.org/2023/formulas/mathematics/college/c7jjt5znjv36px5kzuty5r3hcyxlu178o3.png)
d) Replacing the value x = 58,000 in the equation of the line, we get:
![\hat{y}=38,257-0.1629\cdot58,000=28,808.8.](https://img.qammunity.org/2023/formulas/mathematics/college/3jwr5qgkjdxcee4tcbp02fmo8i8wpdv37x.png)
The residual is the difference between the y coordinate of the point (58,000, $30,000) and the value of y^ that we have computed:
![\text{Residual = }y-\hat{y}=30,000-28,808.8=1,191.2](https://img.qammunity.org/2023/formulas/mathematics/college/lfwwnn6h2qw3rjb78ejfm55iusiextghw6.png)
Answers
a) The price for 100,000 driven is $21,967.
b) The slope of the line is the price per unit of a mile driven:
![m=-0.1629\cdot\frac{\text{units of price}}{\text{miles driven}}\text{.}](https://img.qammunity.org/2023/formulas/mathematics/college/o8g4k06v5g27w7yewx580f1bejf2u4j9xm.png)
c) The y-intercept of the line is the cost of when the number of miles driven is zero:
![b=38,257\text{ units of price.}](https://img.qammunity.org/2023/formulas/mathematics/college/c7jjt5znjv36px5kzuty5r3hcyxlu178o3.png)
d) Residual = $1,191.2.