Desire 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. Assume 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 want to estimate the populations mean travel-to-work time for San Francisco residents with a margin of error of two minutes, what sample size should be used? Suppose 95 percent confidence.
b) If we want 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? Assume 95 percent confidence.