By my calculations regarding to the excel spreadsheet of the
case study, it is a 99% probability that the mean payment will fall equal to or
less than 18.1077, because the confidence interval is between 17.1736 to 18.418
therefore, we made the population mean of payment time to be observed as far
less during those sample mean invoices based on the data given to us.
If the population mean payment time came out to 19.5 days,
what would be the probability of observing the sample mean payment time of 65
invoices having a less than or equal to 18.1077 days?
For the 99% confident interval above, the Stockton trucking company
can conclude with a 99% confidence that the population mean payment time for
the new electronic trucking billing system will falls between 17.736 and