The file P10_49.xlsx contains the amount of money spent advertising a product and the number of units sold for eight months.
a. Assume that the only factor influencing monthly sales is advertising. Fit the following three curves to these data: linear (Y = a + bX), exponential (Y = abX), and multiplicative (Y = aXb). Which equation fits the data best?
b. Interpret the best-fitting equation.
c. Using the best-fitting equation, predict sales during a month in which $60,000 is spent on advertising.