After the end of an advertising campaign, the sales of a product is given by S = 600,000e-0.2t where S is weekly sales in dollars and t is the number of weeks since the end of the campaign. (a) Find...

Extracted text: After the end of an advertising campaign, the sales of a product is given by S = 600,000e-0.2t where S is weekly sales in dollars and t is the number of weeks since the end of the campaign. (a) Find the rate of change of S (that is, the rate of sales decay). ds dt (b) From looking at the function and its derivative, explain how you know sales are decreasing. The given function is an exponential ---Select--- model. Additionally, the derivative of the given function is always ---Select---