Answer:
Option C is correct
27.3
Explanation:
Average rate of change A(x) of f(x) over interval [a, b] is given by:
.....[1]
As per the statement:
Given the function:

At x = 3
then;

At x = 15
then;

Substitute these given values in [1] we have;l

Therefore, the average rate of change from x = 3 to x = 15 is, 27.3