Exercise 11.9: A study was made by a retail merchant to determine the relation between weekly advertising expenditures and sales. Advertising Costs ($) Sales ($) 40 385 20 400 25 395 20 365 30 475 50...

Exercise 11.9: A study was made by a retail merchant to determine the relation between weekly advertising expenditures and sales.

With reference to Exercise 11.9, construct

(a) a 95% confidence interval for the average weekly sales when $45 is spent on advertising;

(b) a 95% prediction interval for the weekly sales when $45 is spent on advertising.