Data were collected on monthly sales revenues (in $100s) and monthly advertising expenditures ($1,000s) for a sample of drug stores. The regression line relating revenues (Y) to advertising expenditure (X) is estimated to be = -48.3+9.00x. The correct interpretation of the slope is that for each additional $100 in sales revenue, advertising expenditures decrease by $48.30 $1000 spent on advertising, predicted sales revenue increases by $900 S1 spent on advertising, predicted sales revenue increases by $9,000 $100 spent on advertising, predicted sales revenue increases by $9,000 $1.000 in sales revenue, advertising expenditures decrease by $48.30