please help 17

A 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 time of 96.7 min and a standard deviation of 40,2 min. Assume that the 24 sample values appear to be from a normally distributed population and construct a 90% 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