Answer:
9
Step-by-step explanation:
The rate of change of a function f(x) in the closed interval [ a, b ] is
[tex]\frac{f(b)-f(a)}{b-a}[/tex]
here [ a, b ] = [ 3, 7 ]
f(b) = f(7) = 47 and f(a) = f(3) = 11, hence
rate of change = [tex]\frac{47-11}{7-3}[/tex] = [tex]\frac{36}{4}[/tex] = 9
