The producers of a new toothpaste claim that it prevents more cavities than otehr brands. A random sample of 60 people used this toothpaste for 6 months. The mean number of cavities at their next checkup is 1.5. In the egneral population, the mean number of cavities at a 6 month check-up is 71.73 (Standard deviation for population= 1.12).

a) Is this a one or two tailed test? Explain answer/

b) What are Ho and Ha for this study?

c) compute z obt.

d)What is z cv?

e) Should Ho be rejected? What should the researcher conclude?

f) Determine the 95% confidence level for the population mean, based on the sample mean.