Select the right sample size for a simple random sample.
The travel-5 largest cities in the United States are reported in the 2003 Information Please Almanac. Presume that a preliminary simple random sample of residents of San Francisco is used to develop a planning value of 6.25 minutes for the population standard deviation.
a) If we need to estimate the populations mean travel-to-work time for San Francisco residents with a margin of error of 2 minutes what sample size must be used? Assume 95% confidence.
b) If we need to estimate the populations mean travel-to-work time San Francisco residents with a margin of error of 1 minute what sample size should be used? Presume 95% confidence.