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 90.4 min and a standard deviation of 44.5

min. Assume that the 20sample 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<

(Round to two decimal places as needed.)