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 21 stores this year shows mean sales of 50 units of a small appliance, with a standard deviation of 9.2 units. During the same point in time last year, an SRS of 18 stores had mean sales of 60.028 units, with standard deviation 12.8 units. A decrease from 60.028 to 50 is a drop of about 20%. 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) equation editor Equation Editor <(μ1−μ2)< equation editor Equation Editor (b) The margin of error is equation editor Equation Editor . 2. At a0.05significance level, is there sufficient evidence to show that sales this year are different from last year?

Name: 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 igno 84981
Uploaded: 2023-08-04T02:35:26-08:00
Duration: 2 min 11 s
Channel: Dominador Tan
Description: 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 igno 84981

          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 21 stores this year shows mean sales of 50 units of a small appliance, with a standard deviation of 9.2 units. During the same point in time last year, an SRS of 18 stores had mean sales of 60.028 units, with standard deviation 12.8 units. A decrease from 60.028 to 50 is a drop of about 20%.
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)
equation editor
Equation Editor
<(μ1−μ2)<
equation editor
Equation Editor
(b) The margin of error is
equation editor
Equation Editor
.
2. At a0.05significance level, is there sufficient evidence to show that sales this year are different from last year?

Added by Cristina A.

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