Advertising (in thousands) Profit (in thousands) 5 150 200 9 250 11 325 13 400 15 450 17 500 19 525 1) Find a cubic model, , for the profit (in thousands), where is the advertising expenditure, in thousands of dollars. Do not alter the inputs. Round each coefficient to 2 decimal places. State the function. 2) Find the rate of change function , including proper units. 3) Using the model, find the instantaneous rate of change when $10,000 is being invested in advertising each month. 4) Using the table data, find the average rate of change when the advertising expenditure increases from $9,000 to $11,000