The following data are the amounts that a sample of 15 customers spent for lunch ($) at a fast-food restaurant. Complete parts (a) through (d) below. 7.42 6.33 5.79 6.50 4.89 6.49 5.53 7.85 8.35 8.30 9.48 7.10 6.82 5.88 9.62 a. Construct a 95% confidence interval estimate for the population mean amount spent for lunch ($) at a fast-food restaurant. (Round to two decimal places as needed. Do not include the $ symbol in your answer.)