Question: The widths of 100 elevator rails have been measured The

The widths of 100 elevator rails have been measured. The sample mean and standard deviation of the elevator rails are 2.05 inches and 0.01 inch.
a. Find a 95% confidence interval for the average width of an elevator rail. Do you need to assume that the widths of elevator rails are normally distributed?
b. How large a sample of elevator rails would you have to measure to ensure that you could estimate, with 95% confidence, the average diameter of an elevator rail within 0.01 inch?


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  • CreatedApril 01, 2015
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