Dr. Susan Benner is an industrial psychologist and is currently studying stress in the executives of Internet companies, for which she developed a questionnaire that she believes measures stress. A result of 80 indicates a dangerous level of stress. A sample of 15 executives revealed an average stress level of 89.47 with a standard deviation of 8.08. Calculate a 95% confidence interval to estimate the population mean.
In an experiment designed to measure the time required for an inspector's eyes to become accustomed to the reduced amount of light needed for a penetrating inspection, the average sample time for n = 9 inspectors was 6.32 seconds and the sample standard deviation was 1.65. seconds. Prior to the experiment, it was assumed that the average adaptation time was at least 7 seconds. Assuming that the adaptation time has a normal distribution, what is the conclusion of the hypothesis test? Consider a significance level of 0.05.