clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the drug, 24 subjects had a mean wake me of 92.8 min and a standard deviation of 40.3 min. Assume that the 24 sample values appear to be from a normally distributed population and construct a 95% onfidence 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 ffective? Find the confidence interval estimate. min