I have no clue how this problem relates to the Product Rule - it seems to relate more to average rates. I would really appreciate it if someone would help me understand this and walk me through the steps to get the answer:
In this exercise we estimate the rate at which the total personal income is rising in a metropolitan area. In 1999, the population of this area was 939,200, and the population was increasing at roughly 9500 per year. The average annual income was $30,388 per capita, and this average was increasing at about $1300 per year (a little above the national average of about $1225 yearly). Use the Product Rule and these figures to estimate the rate at which total personal income was rising in the area in 1999.