As health care costs rise and health care systems worldwide become overburdened, patients are made to wait longer for critical procedures. One Canadian study of 539 cardiac patients waiting for cardiac bypass surgery found a mean wait time of 19 days with a standard deviation of ten days (“Wait Times Data Guide,” Ministry of Health and Long-Term Care, Ontario, Canada, 2006; wait time is measured from the date a patient was recommended for surgery to the date surgery was performed). Assuming the data can be considered representative of the Ontario population, construct a 90% CI for the true mean wait time for bypass surgery in Ontario.