Increase in advertising Increase in Sales expenditure (%) %) Mean 6.5 6.7 Standard Error 1.669045921 1.14392807 Median 7 7.4 Mode #N/A #N/A Standard Deviation 4.720774755 3.235517181 Sample Variance 22.28571429 10.46857143Xi Increase in Vi Increase in Xi - X advertising Vi - y (xi - x)2 ( vi - V)2 (xi - x) x (y expenditure (%) Sales (%) 1 0 2.4 -6.5 -4.3 42.25 18.49 27.95 4 7.2 -2.5 0.5 6.25 0.25 -1.25 WN 14 10.3 7.5 3.6 56.25 12.96 27 4 10 9.1 3.5 2.4 12.25 5.76 8.4 9 10.2 2.5 3.5 6.25 12.25 8.75 6 8 4.1 1.5 -2.6 2.25 6.76 -3.9 7 6 7.6 -0.5 0.9 0.25 0.81 -0.45 8 2.7 -5.5 -4 30.25 16 22 Sum 52 53.6 0 0.00 156 73.28 88.5A fast-food chain decided to carry out an experiment to assess the influence of advertising expenditure on sales. Different relative changes in advertising expenditure, compared to the previous year, were mad in eight regions of the country, and resulting changes in sales levels were observed. The companying table shows the results Increase in advertising 0 14 10 g expenditure (%) Increase in Sales 2.4 7.2 10.3 9.1 10.2 4.1 7.6 2.7 (%) You will need to use the printouts from your assignment 3 for the following questions. 1 a. Predict the percent increase in sales if the increase in advertising expenditure is 5% and construct its 95% confidence interval for the mean prediction. Use the values of S,, $, and [(x; -*)' from the answer in assignment 3 to compute the interval as on page 107 of the course packet. b. Construct a 95% confidence interval for the prediction of the actual percent increase in sales if the increase in advertising expenditure is 5%. Use the values of 5,, $, and )(x; - x) from the answer in assignment 3 to compute the interval as page 109 of the course packet. C. Use PHStat to get the prediction printout with a 95% confidence interval if the increase in advertising expenditure is 5%. Based on the printout, write the prediction intervals for the predictions of the mean and the actual percent increase in sales. You can use these answers to check your answers in parts a and b. See the instructions on PHStat on page 113 of the course packet