Formula:
n = {[(z-value)(sd)]/E}^2
a) n = [(1.96 * 6.35)/2]^2
b) n = [(1.96 * 6.35)/1)^2
Calculate. Round to the next highest whole number.
The travel-to-work time for residents of the 15 largest cities in the United States is reported in the 2003 Information Please Almanac. Suppose that a preliminary simple random sample of residents of San Francisco is used to develop a planning value of 6.35 minutes for the population standard deviation.
a. If we want to estimate the population mean travel-to-work time for San Francisco residents with a margin of error of 2 minutes, what sample size should be used? Assume 95% confidence.
b. If we want to estimate the population mean travel-to-work time for San Francisco residents with a margin of error of 1 minute, what sample size should be used? Assume 95% confidence.
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