Researchers were interested in the stability of a drug product stored for four lengths of time (1, 3, 6, and 9 months). The drug was manufactured with 30 mg/ mL of the active ingredient of a drug product, and the amount of the active ingredient in the drug at the end of the storage period was to be determined. The drug was stored at a constant temperature of 30° C. Two lab-oratories were used in the study, with three 2- mL vials of the drug randomly assigned to each of the four storage times. At the end of the storage time, the amount of the active ingredient was determined for each of the vials. A measure of the pH of the drug was also recorded for each vial. The data are given here.

a. Write a model relating the pH measured on each vial to the factors of length of storage time and laboratory.
b. Display an analysis of variance table for the model of part (a).

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Time (in months mg/mL of Active Time (in months mg/imL of Active at 30C) Laboratory Ingredient pH at 30C) Laboratory Ingredient pH 30,12 3.87 30.10 3.30 30,02 3.84 29.90 3.70 29.95 3.80 29,85 3.75 29.75 3.90 29.85 3.90 29.80 3.90 29.75 3.77 29.85 3.74 29.80 3.76 30,03 3.61 30,10 3.60 0.14 357 30.10 350 3 30.18 3453 30.23 3.48 3 0.03 3.56 30.03 3.74 29.96 381 29.81 3609 29.79 355 9 29.82 3.59