A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. after treatment with the drug, 13 subjects had a mean wake time of 96.6 minutes and a standard deviation of 41.4 minutes. assume that the 13 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. Find the confidence interval estimate