The Excel file Mortgage Rates contains timeseries data on rates of three different mortgage instruments. Assuming that

Question:

The Excel file Mortgage Rates contains time‐series data on rates of three different mortgage instruments. Assuming that the data are stationary, construct a 95% confidence interval for the mean difference between the 30‐year and 15‐year fixed rate mortgage rates. Based on this confidence interval, would you conclude that there is a difference in the mean rates?