When bonding teeth, orthodontists must maintain a dry field. A bonding adhesive (called "Smartbond") has been developed to eliminate the necessity of a dry field. However, there is concern that the new bonding adhesive is not as strong as the current standard, a composite adhesive (Trends in Biomaterials & Artificial Organs, Jan. 2003). Tests on a sample of 10 extracted teeth bonded with the new adhesive resulted in a mean breaking strength (after 24 hours) of x̅ = 5.07 Mpa and a standard deviation of s = .46 Mpa, where Mpa = megapascal, a measure of force per unit area.
a. Orthodontists want to know if the true mean breaking strength of the new bonding adhesive is less than 5.70 Mpa, the mean breaking strength of the composite adhesive. Conduct the appropriate analysis for the orthodontists. Use a = .01.
b. In addition to requiring a good mean breaking strength, orthodontists are concerned about the variability in breaking strength of the new bonding adhesive. Conduct a test to determine whether the breaking strength variance differs from .5 Mpa.