The owner of a restaurant is concerned about customers who ask for a water cup when placing an order but fill the cup with a drink from the beverage fountain instead of filling the cup with water. The owner randomly selected 90 people who order a water cup and found that 21 of those customers filled the cup with a soft drink. a. Construct and interpret a 95 percent confidence interval for the proportion of all customers who, having asked for a water cup when placing an order, will fill the cup with a soft drink from the beverage fountain. b. The owner estimates that each customer who asks for a water cup but fills it with a soft drink costs the restaurant $0.35. Suppose that in the month of June 2,500 customers ask for a water cup when placing an order. Use the confidence interval constructed in part (a) to give an interval estimate for the cost to the restaurant for the month of June from the customers who ask for a water cup but fill the cup with a soft drink.