Four runners were randomly sampled and their time spent running per week was determined. If running times per week for the population of similar runners is normally distributed, and these four runners ran 21, 21, 21, and 13 miles per week, respectively, construct a 95% confidence interval for the population mean. (14.294, 23.706) (12.636, 25.364) (16.647, 21.353) O (15.818, 22.182) (13.448, 24.552)