In: Statistics and Probability
(1 point) A market research firm supplies manufacturers with estimates of the retail sales of their products from samples of retail stores. Marketing managers are prone to look at the estimate and ignore sampling error. An SRS of 11 stores this year shows mean sales of 58 units of a small appliance, with a standard deviation of 7 units. During the same point in time last year, an SRS of 14 stores had mean sales of 51.21 units, with standard deviation 13.5 units. An increase from 51.21 to 58 is a rise of about 12%. 1. Construct a 99% confidence interval estimate of the difference μ1−μ2, where μ1 is the mean of this year's sales and μ2 is the mean of last year's sales. (a) <(μ1−μ2)< (b) The margin of error is