(a)The line of best-fit drawn intercepts the y-axis at 60.
To determine the slope, we use the points (3,65) and (8,70).
[tex]\text{Slope}=\frac{Change\text{ in y}}{\text{Change in x}}=\frac{70-65}{8-3}=\frac{5}{5}=1[/tex]
Therefore, an equation for the line in slope-intercept form is: y=x+60
(b)Since the y-intercept = 60, we have that the initial graduation rate is 60% and it increases at a rate of 1% per year.
(c)To determine the graduation rate in 2020
2020 - 1998 = 22
x=22
Therefore, the graduation rate in 2020 will be:
y=22+60
y=80%
