8.23 A manufacturing company produces chocolate bars. The table below contains the cost per ounce ($) for a sample of 14 dark choco- late bars. 0.63 0.79 0.95 1.19 1.45 0.94 0.78 0.53 1.58 0.53 0.61 0.73 1.52 0.81 a. Construct a 99% confidence interval estimate for the popula tion cost per ounce ($) of dark chocolate bars. b. What assumption do you need to make about the population distribution to construct the interval in (a)? c. Given the data presented, do you think the assumption needed in (a) is valid? Explain