Regress sales per capita on advertising expenditure per capita, controlling for local income as an interval variable, where intervals are <$35,000, $35,000$44,999, $45,000$54,999, and $55,000+, and <$35,000 is the base group.

For the remainder of the question, assume the data-generating process is

SalesperCapitai = + 1AdExpperCapitai + 2Inc35-45i + 3Inc45-55i + 4Inc55i + Ui and that all other necessary assumptions toward establishing causality and performing inference hold.

1.)Interpret the coefficients for the income intervals from your regression.?

2.) According to this regression, what is the effect on sales per capita when average local income increases from $35,000$44,999 to $55,000+?