During a routine check of the fluoride content of gotham city's water supply, the given results were obtained from replicate analyses of a single sample: 0.91500 mg/l , 0.88900 mg/l , 0.91100 mg/l , 0.88900 mg/l , and 0.91900 mg/l . determine the mean and 90% confidence interval for the average fluoride concentration in this sample. report the mean and the confidence interval with three significant figures. mean: 0.905 mg/l 90% confidence interval: ± 0.0124 mg/l