Problem: The Payment Time Case
Review the Payment Time Case Study and Data Set.
Develop 600 words report including the following calculations and using the information to determine whether the new billing system has reduced the mean bill payment time:
a) Assuming the standard deviation of the payment times for all payments is 4.2 days, construct a 95% confidence interval estimate to determine whether the new billing system was effective. State the interpretation of 95% confidence interval and state whether or not the billing system was effective.
b) Using the 95% confidence interval, can we be 95% confident that µ ≤ 19.5 days?
c) Using the 99% confidence interval, can we be 99% confident that µ ≤ 19.5 days?
d) If the population mean payment time is 19.5 days, what is the probability of observing a sample mean payment time of 65 invoices less than or equal to 18.1077 days?
The response should include a reference list. Double-space, using Times New Roman 12 pnt font, one-inch margins, and APA style of writing and citations.