Problem 9E

The article “Drying 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.

CHEMISTRY NOTES- CHAPTER ONE AND TWO UNITS: quantities used to specify measurements SI UNITS MEASUREMENT UNIT SYMBOL Length Meter m Mass Kilogram kg Time Second s Temperature Kelvin K Energy Joule J Amount of substance Mole mol (package) PREFIX’ FOR UNITS PREFIX SYMBOL MULTIPLIER Kilo- k 1000 (10^3) Deci- d 0.1 (10^-1) Centi-