. An article in Rubber Chemistry and Technology (Vol. 47. 1974, pp.

825-836) describes an experiment that studies the relationship of the Mooney viscosity of rubber to several variables, including silica filler (parts per hundred) and oil filler (parts per hundred). Some of the data from this experiment are shown here, where

(a) What type of experimental design has been used? Is it rotatable?

(b) Fit a quadratic model to these data.
What values of x1 and x2 will maxi-
mize the Mooney viscosity?

Transcribed Image Text:

silica-60 oil-21 x2 15 1.5 Coded Levels AL -1 x2 y -1 13.71 1 -1 14.15 7-730000 1 12.87 1 1 13.53 -1.4 1.4 0 0 oooooo 12.99 13.89 -1.4 14.16 1.4 12.90 0 13.75 0 13.66 13.86 13.63 0 0 13.74