9.28 The file Fastfood contains the amount that a sample of nine customers spent for lunch ($) at a fast-food restaurant: 4.20 5.03 5.86 6.45 7.38 7.54 8.46 8.47 9.87 a. At the 0.05 level of significance, is there evidence that the mean amount spent for lunch is different from $6.50? b. Determine the p-value in (a) and interpret its meaning. c. What assumption must you make about the population distribution in order to conduct the 1 test in (a) and (b)? d. Because the sample size is 9, do you need to be con- cerned about the shape of the population distribution when conducting the t test in (a)? Explain