# discussion q and a

These are the questions from my professor that I need to answer (minimum 100 words):

**This week we will study Inferential Statistics**

**including both**

*Confidence Intervals***and**

*Hypothesis Testing*

**.**1. Example Confidence Interval Problem– *Example Exercise*

* *

A gasoline station owner wanted to estimate the mean number of gallons sold per customer. He selected a random sample of 60 customers and found a mean of 8.6, with a Standard Deviation of 2.3. What would be the 95% Confidence Interval for his sampling?

8.6 +/- 1.96 (2.3/)

= 8.6 +/- 1.96 (2.3/7.75)

= 8.6 +/- 0.58

= 8.02 to 9.18

So there is a 95% probability that the true mean of gallons purchased would be between 8.02 and 9.18. Why is this range so wide? The 2.3 gallon *Standard Deviation *found in the sample is large relative to the Mean and contributes to the range. You may want to use *the t Statistic* if you do not have the *Population Standard Deviation* for the problem.

2. Set Up One-Sample Hypothesis Test- We begin with *One-Sample*** Hypothesis Testing**. We have learned to set up the

*and*

**Null***hypothesis, then conduct a test. In research we use this process to test for significant differences or to test a claim made about the*

**Alternative**

**Population Parameter(s).**Discuss some data or claim you would like to test and set up the * Null *and

*hypothesis for it and tell how you would conduct the test using the Z statistic.*

**Alternative**What do you expect to result from the test?

3. Z or t? The first hypothesis testing methods we study are the *Standard Normal or Z* and the Student’s *t. *The first statistic was discussed last week under Continuous Probabilities. You may want to compare and contrast these two distributions.

When do we use Z and when do we test with *t*?