The following data are the amounts that a sample of 15 customers spent for lunch ($) at a fast-food restaurant. Complete parts (a) through (d) below. 7.38 6.31 5.86 6.54 8.32 9.44 7.05 6.77 5.93 4.87 6.55 5.49 7.86 8.36 9.67 a. Construct a 95% confidence interval estimate for the population mean amount spent for lunch ($) at a fast-food restaurant. SHS] (Round to two decimal places as needed. Do not include the $ symbol in your answer.)