A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. Alter treatment with the drug, 24 subjects had a mean wake time of 93.1 min and a standard deviation of41.3 min. Assume that the 24 sample values appear to be from a nonhalhr distributed population and construct a 98% condence 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 eecve? Find the condence interval estimate. min