Writing hypotheses: for each research claim, write the null and the alternative hypotheses:

1. A university publicizes that the proportion of its students who graduate in four years is 82%.
2. A cereal company advertises that the mean weight of the contents of its 20-ounce size cereal boxes is more the 20 ounces.
3. A radio station publicizes that its proportion of the local listening audience is greater than 39%.

1. Hypothesis testing using Z Write, complete each of the five steps of hypothesis testing.

Suppose that scores on the Scholastic Aptitude Test (SAT) form a normal distribution with = 500 and = 100. A high school counselor had developed a special course designed to boost SAT scores. A random sample of n = 16 students is selected to take the course and then the SAT. The sample had an average score of M = 554. Does the course have an effect on SAT scores?

1. Hypothesis testing using t: One-sample

We test if artificial sunlight during the winter months lowers one's depression. Without the light, a depression test has = 8. With the light, our sample with N = 41 produced M = 6.

The t value = -1.83.

1. What are the hypotheses?
2. What is the critical value?
3. What is the test statistic?
4. What is the decision?
5. State the conclusion.

1. Hypothesis testing using t: Two-sample

We test whether "cramming" for an exam is harmful to grades. Condition 1 crams for a pretend exam, but condition 2 does not. Each sample has n = 31. The cramming mean = 43 with a standard error of the mean = 64. The no-cramming mean is 48 with a standard error of the mean = 83.6.

1. What is the independent variable?
2. What is the dependent variable?
3. Write the hypotheses.
4. Will t be positive or negative?
5. Compute t
6. What is your decision?
7. What do you conclude about this study?