In this problem, we have the following equation:
$$\hat{y}=P(x)=38,257-0.1629\cdot x.$$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:
b) The general equation of a line is:
Where:
• b = y-intercept,
,
• m = slope.
Comparing the general equation with the equation of the problem, we have:
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:
c) Comparing the equation of the problem and the general equation of a line, we find the value of the y-intercept:
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:
d) Replacing the value x = 58,000 in the equation of the line, we get:
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:
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:
c) The y-intercept of the line is the cost of when the number of miles driven is zero:
d) Residual = $1,191.2.