Hypothesis testing

PaymentTimeCase4.docx

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Purpose of Assignment

The purpose of the assignment is to develop students' abilities in using data sets to apply the concepts of sampling distributions and confidence intervals to make management decisions.

Assignment Steps

Resources: Microsoft Excel®, The Payment Time Case Study , The Payment Time Case Data Set

Review the Payment Time Case Study and Data Set.

Answer all questions below in word document with the following calculations and using the information in the case study and data set to determine whether the new billing system has reduced the mean bill payment time:

· 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.

· Using the 95% confidence interval, can we be 95% confident that µ ≤ 19.5 days?

· Using the 99% confidence interval, can we be 99% confident that µ ≤ 19.5 days?

· 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?