Answer:
12
Step-by-step explanation:
The average rate of change of a function is the slope because
let [tex]g(x) = f'(x)[/tex]
[tex]\frac{\int\limits^b_a {g(x)} \, dx }{b-a} = \frac{f(b)-f(a)}{b-a}[/tex]
so we just need to calculate the slope of the function over the interval [3, 5]
[tex]\frac{f(5)-f(3)}{5-3} = \frac{37 - 13}{2} = \frac{24}{2} = 12[/tex]