Assignment:
A film alliance used a random sample of 50 U.S. citizens to estimate that the typical American spent 78 hours watching videos and DVDs last year. The standard deviation of this sample was 9 hours.
How large a sample should be used to be 90 percent confident the sample mean is within 1.0 hour of the population mean? (Round your answer to the next whole number.)
Provide complete and step by step solution for the question and show calculations and use formulas.