To find the average rate of change for a quadratic function over a given interval, we need to calculate the slope of the line connecting the two endpoints of the interval.
In this case, the interval is from x = 3 to x = 5. Let's denote the function as f(x).
The average rate of change is given by the formula: (f(5) - f(3))/(5 - 3).
To find f(5), substitute x = 5 into the quadratic function. To find f(3), substitute x = 3 into the quadratic function.
Once you have these values, calculate the difference between f(5) and f(3), and divide it by the difference between 5 and 3.
Finally, simplify the expression and determine the correct option from the given choices.