Question

We use the t distribution to construct a confidence interval for the population mean when the underlying population standard deviation is not known. Under the assumption that the population is normally distributed, find tα∕2,df for the following scenarios. Use Table 2. (Round your answers to 3 decimal places.) tα/2,df a. A 90% confidence level and a sample of 9 observations. b. A 95% confidence level and a sample of 9 observations. c. A 90% confidence level and a sample of 27 observations. d. A 95% confidence level and a sample of 27 observations.

Answer 1

The degree of freedom is, df=n-1=9-1=8

a) Look at intersection of df=8 and C-level = 90%.

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b) Look at intersection of df=8 and C-level = 95%.

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The degree of freedom is, df=n-1=27-1=26

c) Look at intersection of df=26 and C-level = 90%.

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d) Look at intersection of df=26 and C-level = 95%.