1. The producers of a new toothpaste claim that it prevents more cavities than other brands of toothpaste. A random sample of 60 people used the new toothpaste for 6 months. The mean number of cavities at their next check up is 1.5. In the general population, the mean number of cavities at a 6 month checkup is 1.73 (σ =1.12).

a. Is this a one or two-tailed test?

b. What are Ho and h2 or this study?

c. Compute Zobt

d. What is Zcv?

2. Henry performed a two-tailed test for an experiment in which N = 24. He could not find his table of t critical values, but he remembered the tcv at df = 13. He decided to compare his tabt with this tcv. Is he more likely to make a Type I or a Type II error in this situation?

3. A researcher believes that the percentage of people who exercise in California is greater then the national exercise rate. The national rate is 20%. The researcher gathers a random sample of 120 individuals who live in california and finds that the number who exercise regularly is 31 out of 120.

a. What is X2 obt?

 b. what is df for this test?

 c. What is X2 cv?

 d. What conclusion should be drawn from these results?