Question

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 22 stores this year shows mean sales of 85 units of a small appliance, with a standard deviation of 11.2 units. During the same point in time last year, an SRS of 25 stores had mean sales of 74.136 units, with standard deviation 5.1units. An increase from 74.136 to 85 is a rise of about 13%.

1. Construct a 95% 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

Answer 1

The solution is done showing all steps with calculations and required explanations. Hope you can understand.