Question

ind t_α,df from the following information. [You may find it useful to reference the t table.]

		tα,df
a.	α = 0.005 and df = 18
b.	α = 0.20 and df = 18
c.	α = 0.005 and df = 22
d.	α = 0.20 and df = 22

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 t_α/2,df for the following scenarios. (You may find it useful to reference the t table. Round your answers to 3 decimal places.)

		tα/2,df
a.	A 95% confidence level and a sample of 19 observations.
b.	A 90% confidence level and a sample of 19 observations.
c.	A 95% confidence level and a sample of 9 observations.
d.	A 90% confidence level and a sample of 9 observations.
A random sample of 22 observations is used to estimate the population mean. The sample mean and the sample standard deviation are calculated as 107.5 and 22.50, respectively. Assume that the population is normally distributed. [You may find it useful to reference the t table.] a. Construct the 90% confidence interval for the population mean. (Round intermediate calculations to at least 4 decimal places. Round "t" value to 3 decimal places and final answers to 2 decimal places.) b. Construct the 95% confidence interval for the population mean. (Round intermediate calculations to at least 4 decimal places. Round "t" value to 3 decimal places and final answers to 2 decimal places.) c. Use your answers to discuss the impact of the confidence level on the width of the interval. As the confidence level increases, the interval becomes narrower. As the confidence level increases, the interval becomes wider

Answer 1