I need help with question "c".

Americans spend nearly $7 billion on Halloween costumes and decorations. Sample data showing the amount, in dollars, 16 adults spent on a Halloween costume are contained in the Excel Online file below. Construct a spreadsheet to answer the following questions. X Open spreadsheet a. What is the point estimate of the population mean amount adults spend on a Halloween costume (to 2 decimals)? $ 41.37 b. What is the sample standard deviation (to 2 decimals)? $ 23.06 c. Provide a 95% confidence Interval estimate of the population standard deviation for the amount adults spend on a Halloween costume (to 2 decimals)? $ SOS$\f