# Statistics normal distribution | statistics

In this module, you explore the normal distribution. A standard normal distribution has a mean of zero and standard deviation of one. The z-score statistic converts a non-standard normal distribution into a standard normal distribution allowing us to use Table A-2 in your textbook and report associated probabilities.

This discussion combines means, standard deviation, z-score, and probability. You are encouraged to complete the textbook reading and start the MyStatLab Homework before starting this discussion.

### Scenario

The following table reports simulated annual flying squadron costs (in millions of dollars) at the following locations:

__Text description of the Annual Squadron Flying Costs in Millions (PDF)__

### Complete

Use Microsoft Excel and StatDisk to complete the Flying Squadron Costs table for the aircraft type listed below:

- Complete the costs using the B-52 data; use the Kadena data point in your z-score and probability calculations.

Report your values to two decimal places (i.e., 0.12) except for probability. Report probability values to four decimal places (i.e. p = 0.1234).

Your StatDisk results should look similar to this image:

### Post & Discuss

Post the **images** of your spreadsheet and StatDisk results in the discussion area along with a narrative of your findings and the responses to the questions below.

- Do these costs appear to come from a population that has a normal distribution? Why or why not?
- Can the mean of your data sample be treated as a value from a population having a normal distribution? Why or why not?
- Did an “unusually low” or “unusually high” z-score value occur?
- Was the associated z score probability value less than 0.05 (p < 0.05); meaning a “significantly low” or “significantly high” event? If yes, what are the implications for the base and/or aircraft?
- What were your findings? Hint: focus on the calculated mean, standard deviation and z-score (include probability) to interpret your results.