1. A transportation company wants to estimate the average length of time goods are in transit across the country. A random sample of 20 shipments gives x = 2.6 days and s = 0.4 day. Give a 99% con?dence interval for the average transit time.
2. To aid in planning the development of a tourist shopping area, a state agency wants to estimate the average dollar amount spent by a tourist in an exist- ing shopping area. A random sample of 56 tourists gives x = $258 and s = $85. Give a 95% con?dence interval for the average amount spent by a tourist at the shopping area.
3. According to Money, the average home in Ventura County, California, sells for $647,000.9 Assume that this sample mean was obtained from a random sample of 200 homes in this county, and that the sample standard deviation was $140,000. Give a 95% confidence interval for the average value of a home in Ventura County.