A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with thedrug, 14 subjects had a mean wake time of 93.9 min and a standard deviation of 43.9 min. Assume that the 14 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 iseffective?

Find the confidence interval estimate.

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(Round to two decimal places asneeded.)