The article Drying of Pulps in Sprouted Bed: Effect of Composition on Dryer Performance (M. Medeiros, S.

The article €œDrying of Pulps in Sprouted Bed: Effect of Composition on Dryer Performance€ (M. Medeiros, S. Rocha, et al., Drying Technology, 2002:865€“881) presents measurements of pH, viscosity (in kg/m · s), density (in g/cm³), and BRIX (in percent). The following MINITAB output presents the results of fitting the model

a. Predict the pH for a pulp with a viscosity of 1500 kg/m · s, a density of 1.04 g/cm³, and a BRIX of 17.5%.

b. If two pulps differ in density by 0.01 g/cm³, by how much would you expect them to differ in pH, other things being equal?

c. The constant term β₀ is estimated to be negative. But pulp pH must always be positive. Is something wrong? Explain.

d. Find a 95% confidence interval for the mean pH of pulps with viscosity 1200 kg/m · s, density 1.08 g/cm³, and BRIX 18.0%.

e. Find a 95% prediction interval for the pH of a pulp with viscosity 1000 kg/m · s, density 1.05 g/cm³, and BRIX 19.0%.

f. Pulp A has viscosity 2000, density 1.03, and BRIX 20.0. Pulp B has viscosity 1000, density 1.05, and BRIX 19.0. Which pulp will have its pH predicted with greater precision? Explain.

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pH = Bo + B, Viscosity + B, Density + B, BRIX + ɛ