A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the drug, 13 subjects had a mean wake time of 90.8 min and a standard deviation of 40.3 min. Assume that the 13 sample values appear to be from a normally distributed population and construct a 98% confidence interval estimate of the standard deviation of the wake times for a population with the drug treatments. Does the result indicate whether the treatment is effective? Find the confidence interval estimate. min < o < min (Round to two decimal places as needed.)