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 98.7 min and a standard deviation of 43.6 min. Assume that the 11 sample values appear to be from a normally distributed population and construct a 98% 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

min<

(Round to two decimal places asneeded.)

To determine whether the result indicates whether the treatment iseffective, interpret the interval. Recall that a confidence interval(or intervalestimate) is a range(or aninterval) of values used to estimate the true value of a population parameter. The confidence level is the probability 1 that the confidence interval actually does contain the population parameter.