An advertising firm wishes to demonstrate to its clients the effectiveness of the advertising campaigns it has conducted. The following bivariate data on twelve recent campaigns, including the cost of each campaign (in millions of dollars) and the resulting percentage increase in sales following the campaign, were presented by the firm. Based on these data, we would compute the least-squares regression line to be y - 6.24 +0.15x, with x representing campaign cost and y representing the resulting percentage increase in sales. (This line is shown below, along with a scatter plot of the data.) Campaign cost, x Increase in sales, y (in millions of dollars) (percent) 2.00 6.50 2.99 6.86 2.43 6.57 1.68 6.22 3.86 6.74 Increase in sales (percent) 3.28 6.44 4.12 6.95 2.92 6.64 1.38 6.34 3.54 6.91 1.96 6.82 Campaign cost 1.44 6.67 (in millions of dollars) Send data to calculator Send data to Excel Based on the firm's data and the regression line, answer the following. (a) What was the observed percentage increase in sales when the advertising campaign cost was 1.44 million dollars? (b) From the regression equation, what is the predicted percentage increase in sales when the advertising campaign cost is 1.44 million dollars? Round your answer to two or more decimal places