Answer Happy

The length of time it takes for Neater Feet to sell a pair of walking boots has an unknown mean of μ days and known standard deviation o = 3.12 days. We wish to create a confidence interval for μ. We randomly select 10 pairs of walking boots at Neater Feet stores and measure time to sale. The sample mean was x = 17.12 days and the sample standard deviation was s = 3.91 days. a) What is the critical value for a 95% confidence interval for μ? b) Create a 95% confidence interval for μ How long is the 95% confidence interval for μ? d) How many observations would we need to guarantee that the 95% confidence interval above has a length of 2.0 or less? e) Create a 95% prediction interval for using this data. f) Assuming o is not known, create a 95.0% confidence interval for using this data. g. What is the length of the confidence interval for part f? h) Copy your R script for the above into the text box here.