Answer
$P\left( x \right)=0.725x+18$
Work Step by Step
The graph between the percentage of grade and the grade shows the percentage of grades A and C of students in the years 1968 and 2008.
Consider the general slope-intercept form of the linear function:
$P\left( x \right)=mx+b$
Here, $m$ is slope of the curve plotted by the function, $b$ is the y-intercept, and x is the variable that represents year after 1968.
The increase in the average rate represents the slope of the curve on the graph. It shows that $m=0.725$and the b y-intercept is \[18%\].
Substitute the values in the above equation:
$P\left( x \right)=0.725x+18$
Here, the above function is the linear function in the slope-intercept form.
The above function models the percentage of the particular high school grade of students entering college x years after the year 1968.
