The producers of a new toothbrush claim that it prevents more cavities than other brands of toothpaste. A random sample of people used the new toothpaste for 6 months. The mean number of cavities at the next checkup is 1.5. In the general population, the mean number of cavities at a 6 month check-up is 1.73 (α - 1.12).
a) Is this a one - or two tailed test?
b) What are H0 and Ha for this study?
c) Compute Z obt.
d) What is Z cv?
e) Should H0 be rejected? What should the researcher conclude?
f) Determine the 95% confidence interval for the population mean, based on the sample mean.