A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the drug, 21 subjects had a mean wake time of 93.3 min and a standard deviation of 44.7 min. Assume that the 21 sample values appear to be from a normally distributed population and construct a 95% 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?

Question: Find the confidence interval estimate.