Question

The function below shows the number of car owners f(t), in thousands, in a city in different years t:
f(t) = 1.1t2 − 2.5t + 1.5
The average rate of change of f(t) from t = 3 to t = 5 is thousand owners per year.

Answer 1

yikes meant to get to this earlier

anyway, average rate of change from a to b for a general function f(x) is

[f(b) - f(a)]/(b-a)

applying this logic to your problem

[f(5) - f(3)]/(5-3)

*** important note *** f(5) minus f(3) is not f(2), you have to calculate f(5) and f(3) separately