The function below shows the number of car owners f(t), in thousand, in a city in different years t:
f(t) = 0.25t2 - 1.5t + 2.5
The average rate of change of f(t) from t = 5 to t = 8 is ______ thousand per year
f(t) = 0.25t2 - 1.5t + 2.5
The average rate of change of f(t) from t = 5 to t = 8 is ______ thousand per year