A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the​ drug, 20 subjects had a mean wake time of 91.8 min and a...

A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the​ drug,

subjects had a mean wake time of

min and a standard deviation of

min. Assume that the

sample values appear to be from a normally distributed population and construct a

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?