g an independent group of food service personnel conducted a survey on tipping practices in a large metropolitan area. they collected information on the percentage of the bill left as a tip for 25 randomly selected bills. the average tip was 14.3% of the bill with a standard deviation of 2.7%. assume that the tips are approximately normally distributed. construct an interval to estimate the true average tip (as a percent of the bill) with 95% confidence. round the endpoints to two decimal places, if necessary.