(16) 1. A chemical engineer is interested in determining the operating conditions that maximize the yield of a process. Two controllable variables that influence yield are reaction time and reaction temperature. Using coded variables of 21=(time-85)/5 in minutes, and z2= (temperature-175)/5 in degrees F, the 13 values of (In, I12, Mi) Are: r1 -1 -1 76.2 0 0 79.6 -1 1 76.8 0 0 79.8 1 -1 78.2 1.414 78.5 1 79.3 -1.414 76.1 0 0 80.0 1.414 78.8 0 0 80.4 -1.414 77.3 80.1 Two models are fit to these data: (A) Y. = 8+ Pirn + Are + Bark + Bash + Asmaca +e, and (B) Some summaries from R are as follows: fit1=lm(y"x1+x2+I(x1 2)+I (x2-2)+x1 :x2) Estimate Std. Error t value Pr(>It[) (Intercept) 79. 9800 0. 1251 639.31 It[) (Intercept) 79. 9800 0. 1235 647.51