Since we have a linear relationship between these variables, we can find the slope of these linear relationship using any combination of two points from the table. We can select the points:
x1 = 0, y1 = 50
x2 = 2, y2 = 40
(We can also can get x1 = 0, y1 = 50, and x2 = 4, y2 = 30, and we can get the same result).
The formula for the slope in a linear relationship is as follows:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
And then, using the previous values (without using units):
[tex]m=\frac{40-50}{2-0}\Rightarrow m=\frac{-10}{2}\Rightarrow m=-5[/tex]
Therefore, the slope for this linear relationship is negative (as far as time passes the water level is less and less), and the value for this is m = -5 ft per hr.
