sample containing years to maturity and yield for 40 corporate bonds is contained in the Excel Online file below. Construct a spread Open spreadsheet a. What is the sample mean years to maturity for corporate bonds and what is the sample standard deviation? Mean (to 4 decimals) Standard deviation (to 4 decimals) b. Develop a 95% confidence interval for the population mean years to maturity. Please round the answer to four decimal places. years c. What is the sample mean vield on corporate bonds and what is the sample standard deviation? Mean (to 4 decimals) Standard deviation (to 4 decimals) d. Develop a 95% confidence interval for the population mean vield on corporate bonds please rourid the answer to four decimal places