How do you find the average rate of change of a function over an interval?

Average rate of change over an interval =

(difference in value of the function between the

beginning and end of the interval)

divided by

(length of the interval).

Example:

If the function was 200 pounds at the beginning, and 98 pounds 3 hours later,

then the average rate of change is (98 - 200) / 3 = - 34 pounds per hour.