In 2017, Americans spent a record-high 39.1 billon on Helloween-related purchases (the balance website). Sample data showing the amount, in dollars, 16 adults spent on a Halloween costume are as follows. a. What is the estimate of the population mean amount adults spend on a Halloween costume (to 2 decimals)? 3 b. What is the sample standard deviation (to 2 dedinals)? c. Provide a 95% confidence interval eatimate of the population standard deviation for the amount adults spend on a Halloween costume (to 2 decimals). Use Table 11,1+ 3.