For many years sodium nitrite has been used as a curing agent for bacon, and until recently it was thought to be perfectly harmless. But now it appears that during frying, sodium nitrite induces the formation of nitrosopyrrolidine (NPy), a substance suspected of being a carcinogen. In one study focusing on this problem, measurements were made of the amount of NPy (in ppb) recovered after the frying of three slices of four commercially available brands of bacon (161). Do the analysis of variance for the data in the table and partition the treatment sum of squares into a complete set of three mutually orthogonal contrasts. Let the first contrast test H0: μA = μB and the second, H0: (μA + μB)/2 = (μC + μD)/2. Do all tests at the 0.05 level of significance.

NPy Recovered from Bacon (ppb) Brand 20 40 18 75 25 21 15 30 21 25 30 31