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# Confidence Interval for Population Variance

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1. The mean replacement time for a random sample of 12 microwave ovens is 8.6 years with a standard deviation of 4.2 years. Construct a 98% confidence interval for the population variance o^2. Assume the data are normally distributed.
A. (7.8,63.6) B. (1.9,15.1) C. (2.8,8.0) d. (7.4,54.3)

2. The dean of a major university claims that the mean time for students to earn a Master's degree is at most 3.8 years. It a hypothesis test is performed, how should you interpret a decision that fails to reject the null hypothesis?
A. There is not sufficient evidence to reject the claim that the mean is less than or equal to 3.8
B. there is sufficient evidence to reject the claim that the mean is less than or equal to 3.8.
C. There is not sufficient evidence to support the claim that the mean is less than or equal to 3.8.
d. there is sufficient evidence to support the claim the mean is less than or equal to 3.8.

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#### Solution Summary

The solution provides step by step method for the calculation of confidence interval for population variance. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.

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