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July 28, 2015

Homework Help: statistics/ Help!-thanks!

Posted by StudentD on Saturday, August 25, 2012 at 4:28pm.

The producers of a new toothpaste claim that it prevents more cavities than other brands of toothpaste. A random sample of 60 people use 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 # of cavities after a 6 month check up is 1.73 (@= 1.12).
a) is it 1 or 2 tailed test? (I think one- tailed)
b) What are the Ho and Ha for this study? I think:
Ho: = 1 or cavities from new toothpaste= cavities any other brand toothpaste
Ho: 0>1 or cavities from new toothpaste> cavities with any other brand toothpaste
Ha: 0<1 or cavities from new toothpaste< cavities with any other brand toothpaste

c) Compute Zobt -I don't know how
d) What is Z cv?- Also don't know.
e) Should Ho be rejected (I think yes)
f) Determine the 95% confidence interval for the population mean, based on the sample mean.

Thank you in advance for your help!

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