Qnt 561

University of Phoenix

QNT

### Question Description

I’m trying to learn for my Statistics class and I’m stuck. Can you help?

**urpose 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.** **

**Develop** a 700-word report including the following calculations and using the information 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?

**Submit** your assignment.

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## Final Answer

Please find the attached filed and let me in case you have any concerns

Running Head: BILLING SYSTEM’S EFFECTIVENESS

Billing system’s effectiveness

Name

Date

Institution.

BILLING SYSTEM’S EFFECTIVENESS

2

New Billing System effectiveness.

Introduction.

The management consulting group has recorded over seven thousand invoices for the

first three months. Out of those, our sample consists of only 65 observations. The management

consulting system believes that the new system will cut the invoice processing time by more

than half, which means that the current processing time of thirty-nine days is likely to reduce

to 19.5 days or less. To establish whether that is true, we could compute the mean for the

sample observations as well as the standard deviation to serve as an industry benchmark if

necessary. The other question, however, is if the metrics from the sample data is accurate for

the whole population, for this case, the 7832 invoices. To find whether this is true, we test the

estimates and find the confidence interval to assign Z scores to our evaluations.

Sample Data Metrics and Interpretation.

The mean for the sample data gets computed using the AVERAGE Excel functionality.

It calculates to be 18.11 as per the spreadsheet in the Appendix below. Subsequent variance is

calculated by subtracting the mean from each of the variables in the sample data. Conseque...