whats the average rate of change of h over the interval 5 ≤ t ≤ 9?

Given:
The graph of a function.
To find:
The average rate of change of h over the interval [tex]5\leq t\leq 9[/tex].
Solution:
The average rate of change of a function f(x) over the interval [a,b] is:
[tex]m=\dfrac{f(x_2)-f(x_1)}{x_2-x_1}[/tex]
So, the average rate of change of h over the interval [tex]5\leq t\leq 9[/tex] is:
[tex]m=\dfrac{h(9)-h(5)}{9-5}[/tex]
From the given graph it is clear that [tex]h(9)=7,h(5)=3[/tex]. Substituting these values, we get
[tex]m=\dfrac{7-3}{9-5}[/tex]
[tex]m=\dfrac{4}{4}[/tex]
[tex]m=1[/tex]
Therefore, the average rate of change of h over the interval [tex]5\leq t\leq 9[/tex] is 1.