Customers arrive at a movie theater at the advertised movie time only to find that they haveto sit through several previews and prepreview ads before the movie starts. Many complainthat the time devoted to previews is too long (the Wall Street Journal, October 12, 2012).A preliminary sample conducted by the Wall Street Journal showed that the standarddeviation of the amount of time devoted to previews was 4 minutes. Use that as a planningvalue for the standard deviation in answering the following questions.a. If we want to estimate the population mean time for previews at movie theaters with amargin of error of 75 seconds, what sample size should be used? Assume 95% confidence.b. If we want to estimate the population mean time for previews at movie theaters with amargin of error of 1 minute, what sample size should be used? Assume 95% confidence
Customers arrive at a movie theater at the advertised movie time only to find that they have
to sit through several previews and prepreview ads before the movie starts. Many complain
that the time devoted to previews is too long (the Wall Street Journal, October 12, 2012).
A preliminary sample conducted by the Wall Street Journal showed that the standard
deviation of the amount of time devoted to previews was 4 minutes. Use that as a planning
value for the standard deviation in answering the following questions.
a. If we want to estimate the population mean time for previews at movie theaters with a
margin of error of 75 seconds, what
b. If we want to estimate the population mean time for previews at movie theaters with a
margin of error of 1 minute, what sample size should be used? Assume 95% confidence
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