statistics

A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the drug, 16 subjects had a mean wake time of 95.8 min and a standard deviation of 44.2 min. Assume that the 16 sample values appear to be from a normally distributed population and construct a 95% 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 effective? Find the condence interval estimate. I] min