1. 8.2 Day I: Z-Tests for a Mean One Tailed Large Sample
By the end of class you will be able to conduct a one tailed hypothesis test for means.

2. Sneaker Prices
A researcher claims that the average price of sneakers is less than $80. He randomly selects 36 pairs of shoes and finds the average cost to be $75 with a standard deviation of $19.2. Is there enough evidence to support the researcher’s claim at the significance level of .1

3. Hypothesis Test Steps Identify the claim and hypotheses
Find the critical value (Table E)
Calculate the test value
Determine whether to reject or not reject the null hypothesis
Summarize the results

4. Test Value for Mean:

5. Our Sneaker Example….

6. Helpful Hints A one tailed test uses < or >
Draw a distribution to determine the critical value
Always select the next highest z value if necessary
Never “accept” the null hypothesis

7. The manager of a Pepsi plant claims that each can contains more than12 oz of soda. You check 36 cans and find the cans to contain 12.19oz of soda on average with a standard deviation of .11. Conduct a hypothesis test with a significance level of .01

8. The manager of the PHL airport claims that the average delay time at the airport is less than 30 minutes. Today you sampled 40 flights and found the average delay time to be 33 minutes with a standard deviation of .5 minutes. Conduct a hypothesis test with a significance level of .1 to test the manager’s claim.

9. The Most Important Thing
The most important thing about one tailed hypothesis test for the mean is…..
I need to also remember to …..
And make sure to….
But the most important thing about one tailed hypothesis tests for the mean is….