Question

Refer to the Business and Society (Mar. 2011) study on the sustainability behaviors of CPA corporations. Recall that the level of support for corporat

Confidence intervals
ANSWERED
asked 2021-07-04
Refer to the Business and Society (Mar. 2011) study on the sustainability behaviors of CPA corporations. Recall that the level of support for corporate sustainability (measured on a quantitative scale ranging from 0 to 160 points) was obtained for each in a sample of 992 senior managers at CPA firms. The accompanying MlNITAB printout gives 90% confidence intervals for both the variance and standard deviation of level of support for all senior managers at CPA firms. Statistics
VariableNStDevVariance Support99226.9722
90% Confidence Intervals
VariableMethodCI for StDevCI for Variance SupportChi-Square(25.9, 27.9)(672, 779)
a. Locate the 90% confidence interval for σ2 on the printout.
b. Use the sample variance on the printout to calculate the 90% confidence interval for σ2. Does your result agree with the interval shown on the printout?
c. Locate the 90% confidence interval for a on the printout.
d. Use the result, part a, to calculate the 90% confidence interval for
a. Does your result agree with the interval shown on the printout?
e. Give a practical interpretation of the 90% confidence interval for a.
f. What assumption about the distribution of level of support is required for the inference, part e, to be valid? Is this assumption reasonably satisfied?

Answers (1)

2021-07-05
a) (672,779)
b) (5754.3067,9181.4011),No
c) (25.9,27.9)
d) (75.8571,95.8196),No
e) We are 90% confident that the standart deviation of level of support for all senior managers at CPA firms is between 25.9 and 27.9.
f) Yes
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