Marketing managers are prone to look at the estimate and ignore sampling error. An SRS of 24 stores this year shows mean sales of 83 units of a small appliance, with a standard deviation of 6.6 units. During the same point in time last year, an SRS of 31 stores had mean sales of 76.334 units, with standard deviation 12.5 units. An increase from 76.334 to 83 is a rise of about 8%. 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) (b) The margin of error is <(μ₁-μ₂) < 2. At a 0.05 significance level, is there sufficient evidence to show that sales this year are different from last year? A. Yes OB. No

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.3: Measures Of Spread
Problem 26PFA
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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 24 stores this year shows mean sales of 83
units of a small appliance, with a standard deviation of 6.6 units. During the same point in time last year, an SRS of 31 stores had mean
sales of 76.334 units, with standard deviation 12.5 units. An increase from 76.334 to 83 is a rise of about 8%.
-
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)
(b) The margin of error is
< (μ₁ − µ₂) <
2. At a 0.05 significance level, is there sufficient evidence to show that sales this year are different from last year?
A. Yes
B. No
Transcribed Image Text:Marketing managers are prone to look at the estimate and ignore sampling error. An SRS of 24 stores this year shows mean sales of 83 units of a small appliance, with a standard deviation of 6.6 units. During the same point in time last year, an SRS of 31 stores had mean sales of 76.334 units, with standard deviation 12.5 units. An increase from 76.334 to 83 is a rise of about 8%. - 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) (b) The margin of error is < (μ₁ − µ₂) < 2. At a 0.05 significance level, is there sufficient evidence to show that sales this year are different from last year? A. Yes B. No
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