Question

Mr. Mole left his burrow and started digging his way down at a constant rate.

Answer 1

Constant rate means it is linear so we don't have to worry about fluctuation.

change in y/ change in x=-18-(-25.2)/5-8=2.4 meters per second

Answer 2

We have been given that Mr. Mole left his burrow and started digging his way down at a constant rate. The table compares Mr. Mole altitude relative to the ground (in meters) and the time since he left (in minutes).

Mr. Mole's speed will be equal to slope of line passing through the given points.

$m=\frac{y_2-y_1}{x_2-x_1}$

Let point $(5,-18)=(x_1,y_1)$ and point $(8,-25.2)=(x_2,y_2)$.

Upon substituting these values in slope formula, we will get:

$m=\frac{-25.2-(-18)}{8-5}$

$m=\frac{-25.2+18}{3}$

$m=\frac{-7.2}{3}$

$m=-2.4$  

Mr. Mole's altitude is getting more and more negative as he digging down.

Since speed cannot be negative, therefore, Mr. Mole's speed is 2.4 meters per minute.