The standard deviation of the daily demand for a product is an important factor for inventory control for the product. Suppose that a pharmacy wants to estimate the standard deviation of the daily demand for a certain antibiotic. It is known that the daily demand for this antibiotic follows an approximately normal distribution. A random sample of 18days has a sample mean of 127orders for this antibiotic with a standard deviation of 10.5orders. Find a 90%confidence interval for the population standard deviation of the daily demand for this antibiotic.

What is the lower and upper limits of the 90% confidence interval?