. An experiment was run to study the effect of two factors, time and tempera-

ture, on the inorganic impurity levels in paper pulp. The results of this experi-

ment are shown here:

(a) What type of experimental design has been used in this study? Is the design rotatable?

(b) Fit a quadratic model to the response, using the method of least squares.

(c) Construct the fitted impurity response surface. What values of x1 and x2 would you recommend if you wanted to minimize the impurity level?

(d) Suppose that time - 30 temp-750 50 15 where temperature is in C and time is in hours. Find the optimum oper-
ating conditions in terms of the nat-
ural variables temperature and time.

Transcribed Image Text:

22 y -1 -1 1 -1 210 95 -1 1 218 1 100 -1.5 1.5 0 -15 0 0 0 1007700 225 50 175 1.5 180 145 175 0 0 158 0 0 166