1. Review Unit 7: Hypothesis Testing

2. Things to consider: What is the p-value? What is more serious – Type I error or Type II? How do we choose the level of significance? What does it represent?

3. More things to consider… What is a hypothesis? When do I reject the alternative hypothesis? What’s the difference between t and z?

4. Know: How to write hypotheses What a type I/II error is and the consequences. How to choose the level of significance. What’s the probability of type I/II error called? Be able to run a large sample proportion z- test, 1 sample mean z- test, and a 1 sample mean t-test.

5. Harley-Davidson motorcycles make up 14% of all the motorcycles registered in the United States. You plan to interview an SRS of 500 motorcycle owners. What’s the probability that 20% or more own Harleys?

6. A study found that 48 out of the 200 students surveyed had cheated on a test. Calculate a 90% confidence interval for the true proportion of student who have cheated on a test.

7. Approximately 82% of all students have copied a classmate’s homework. I have a class of 32. How many do you expect to find have copied? What is the probability that exactly 28 have copied? What is the probability that at least 25 have copied? What is the probability that less than 21 have copied?

8. The number of flaws per square yard in a type of carpet material varies with a mean of 1.8 flaws per square yard and st. dev. 1.2 flaws. An inspector studies 200 square yards, what the probability that the mean number of flaws exceeds 2 per square yard?

9. The probability that Ed hits the ball when he goes to bat is 0.23. Find the probability that he doesn’t get a hit until his 3 rd time at bat.

10. If I want to estimate the mean SAT score within 5 points with a 99% confidence, how large of a sample would you need. The standard deviation is 100.

11. The composition of the earth’s atmosphere may have changed over time. The gas in bubbles within amber should be a sample of the atmosphere at the time the amber was formed. The measures on specimens of amber are shown below. Construct and interpret a 95% confidence interval for the mean percent of nitrogen in ancient air. 63.46564.463.354.864.560.8

12. Find the mean and standard deviation of the following: xp(x) 200.02 250.03 300.08 350.12 400.22 45 500.28

13. I want to test my sweet pea seeds to determine the germination rate, that is the percent of seeds that sprout. How large of a sample of seeds will I need to be within 4% of the true proportion?

14. Study for your Test!