Question

A clinical trial was conducted to test the effectiveness of a drug used for treating insomnia in older subjects. After treatment with the​ drug, 15 subjects had a mean wake time of 94.9 min and a standard deviation of 41.5 min. Assume that the 15 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 is​ effective?

Find the confidence interval estimate.

​(Round to two decimal places as​ needed.)

Answer 1

At 98% confidence interval, the critical values are = 4.6604

                                                                               = 29.1412

The 98% confidence interval for is

sqrt((n - 1)s^2/) < < (sqrt(n - 1)s^2/)

= sqrt(14 * (41.5)^2/29.1412) < < sqrt(14 * (41.5)^2/4.6604)

= 28.76 < < 71.93