A company is considering installing fax machine at one

A company is considering installing fax machine at one of its branches. As part of decision process as to whether to install a machine the company manager intends to estimate the average number of documents that would be transmitted daily if the machine was installed. From experience at other branches the manager believes the standard deviation of number of documents sent daily is 32. The machine is tested over a random sample of 15 days and resulting sample mean of 267.
Calculate a 99% confidence interval for average number of documents that would be transmitted daily if machine were installed.
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