Not sure how to figure this, an explanation would be nice

Question 16 A quality control specialist for a restaurant chain wishes to estimate the mean amount of soda being served in 16 oz size cups. 14.3 oz. Assume that the amounts of soda dispensed is normally distributed with a standard deviation of 1.5 oz. a) Use this sample data to construct a 95% confidence interval for the mean amount of soda. b) What is the margin of error for this estimate? c) How large a sample would be needed in order to estimate the mean amount soda with a margin of error of 0.25 ounces? 12 pts She selects a random sample of 32 cups of soda from different franchises, and finds that the sample mean for the amount of soda is