The function f(x)=125(0.9)x models the population of a species of fly in millions after x years. how does the average rate of change between years 11 and 15 compare to the average rate of change between years 1 and 5? a) the average rate of change between years 11 and 15 is about 1/3 the rate between years 1 and 5. b) the average rate of change between years 11 and 15 is about 1/2 the rate between years 1 and 5 . c) the average rate of change between years 11 and 15 is about 3 times the rate between years 1 and 5. d) the average rate of change between years 11 and 15 is about 2 times the rate between years 1 and 5 .