In an effort to increase public acceptance of a light rail system, the manager for City Transit Services in Seattle is interested in estimating the standard deviation for the time it takes a bus to travel between the University of Washington and the downtown bus terminal. To develop an estimate for the standard deviation, he has collected a random sample of the times required for 25 trips. The sample standard deviation is 6.8 minutes. Based on these data, what are the 90% confidence interval estimate for the true population variance and standard deviation?

I. The lower limit of the confidence interval of the population variance is

II. The upper limit of the confidence interval of the population variance is

III.The lower limit of the confidence interval of the population standard deviation is

IV.The upper limit of the confidence interval of the population standard deviation is