A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with thedrug, 11 subjects had a mean wake time of 96.9 min and a standard deviation of 42.8 min. Assume that the 11 sample values appear to be from a normally distributed population and construct a 95% 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.

nothing

minless than

less than