The average rate of change is 247.5. The average rate of change of a function f(x) over the interval x1 to x2 is given by AROC=(f(x2)-f(x1))/(x2-x1). In this case, x1=1 and x2=2. f(1) = 55 and f(2)=302.5. This the average rate of change is given by (302.5-55)/(2-1). When we simplify this, we get that the average rate of change in 247.5.