A random sample of 13 health maintenance organizations (HMOS) was selected. For each HMO, the co-payment (in dollars) for a doctor's office visit was recorded. The results are as follows. 12, 9, 8,...

Extracted text: A random sample of 13 health maintenance organizations (HMOS) was selected. For each HMO, the co-payment (in dollars) for a doctor's office visit was recorded. The results are as follows. 12, 9, 8, 10, 5, 6, 8, 9, 9, 5, 10, 11, 7 Send data to calculator Send data to Excel Under the assumption that co-payment amounts are normally distributed, find a 90% confidence interval for the mean co-payment amount in dollars. Then find the lower limit and upper limit of the 90% confidence interval. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.) Lower limit:|I Upper limit: