Answer:
6
Step-by-step explanation:
The average rate of change of f(x) in the closed interval [ a, b ] is

Here [ a, b ] = [ 3, 4 ]
f(b) = f(4) = 9 ← value of f(x) when x = 4 , from table
f(a) = f(3) = 3 ← value of f(x) when x = 3 , from table
average rate of change =
=
= 6