Suppose that a certain television program has an average point rating of 5.3 (ratings measure the number of viewers), and that the program's executives estimate that a 0.2 drop in the ratings will correspond to a dollar-sign ⁢ 4.1 million drop in revenue. If f left-parenthesis p right-parenthesis is the revenue earned in millions of dollars in terms of p, the ratings points, express this estimation as a derivative.