The population of a city is given by P(t) =1000 + 3t^2 where t is the number of the years after 1990 and P(t)  is the population in thousands.
A) Graph  P(t).
B) What is the average rate of change of population between 1990 and 2000? (Do not forget units!)
(C) Find the instantaneous rate of change of population in the year 1996?