Assessment 2
Use the following files, linked in the Resources under the
Required Resources heading, to complete both of the scenarios for this
assessment:
Confidence Interval Calculator.
Area Gas Prices – Random Sample.
Sample Size Estimator.
Practical Application Scenario 1
To complete this scenario, use the Confidence Interval
Calculator and the Area Gas Prices – Random Sample files.
The Minneapolis Star Tribune newspaper has decided to write
an article about gasoline prices in the Twin Cities area (Minneapolis and Saint
Paul, Minnesota). The Star Tribune has designed a survey and taken a simple random
sample of regular, unleaded gas prices at 70 area stations. The results are in
the Area Gas Prices – Random Sample file. The Star Tribune’s policy is that no
data will be reported unless it is 95 percent confident that the numbers are
correct. As the new manager of the data verification unit at the Star Tribune,
you need to develop a 95 percent confidence interval for the average price of
regular unleaded gasoline in the area.
Complete a confidence interval for the data provided, using
tables to demonstrate your method and findings.
Write a 3–5 sentence summary that communicates your results
to the Star Tribune’s business manager.
Practical Application Scenario 2
To complete this scenario, use the Sample Size Estimator
file.
The third shift at Microsoft Windows’ security unit in
Redmond, Washington, is considering replacing its coffee brewing units with new
German-made brewers. As the newest member of this elite Microsoft team, you
have been assigned to investigate this proposal. Develop a 99 percent
confidence interval for the average yield (cups per pound) for the new German
coffee brewer. The margin of error should be no bigger than .3 (three-tenths of
a cup). Based on experience with the current coffee makers, your best guess for
the population standard deviation, sigma, is 1.2 cups. How large a sample do
you need?
Calculate the estimated sample size needed for the above
scenario, using tables to demonstrate your method and findings.
Write a 3–5 sentence summary that communicates your results to
the business manager.
Additional Requirements
Compile your work for both scenarios in one Microsoft Word
file:
Paste in the tables you used.
Clearly title your tables, including each row and column.
Highlight the results of your data calculations within each
table.
Summarize your findings for each scenario in a 3–5 sentence
paragraph below each table.
