### Confidence interval for the population mean

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##### Reference no: EM1386078

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.

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