10.27 The corrosive effects of various soils on coated and uncoated steel pipe was tested by using a dependent sampling plan. The data collected are summarized by n  40, d  220, d2  6222, where d is the amount of corrosion on the coated portion subtracted from the amount of corrosion on the uncoated portion. Does this random sample provide sufficient reason to conclude that the coating is beneficial? Use   0.01 and assume normality.

a. Solve using the p-value approach.

b. Solve using the classical approach.