A manufacturing engineer is responsible for the production of a chemical additive, XRX, used by one of their customers. The viscosity of the chemical additive is based on the quality of cellulose used in the formulation, the length of the cellulose fibers, and the amount of two materials used in the mixture, cellulose and EO. The engineer has recorded data for 37 lots of production. The engineer wants to estimate the viscosity of XRX based on cellulose quality, fiber length, lbs. of cellulose, and lbs. of EO. The data is shown in Worksheet A4.

XRX Viscosity Cellulose Quality Fiber Length Cellulose (lbs) EO (lbs)
6980 23350 28.2 9945 7250
7240 22771 29.3 9898 7239
6608 23239 32.4 9830 7251
7410 21647 28.9 9939 7231
7040 20236 29.6 9941 7244
7250 20205 28.7 9937 7542
6880 20342 29.7 9981 7992
6910 20747 30.5 9929 7693
7480 20585 38.0 6618 5150
6230 19978 37.0 9908 7694
6520 19882 31.0 9893 7693
6630 19556 35.0 9938 7694
6490 19461 32.8 9933 7684
6345 19619 34.4 9911 7696
6470 20366 32.0 9950 7897
6490 19772 35.7 9906 7244
6490 20383 34.9 9959 7250
6560 20527 35.9 9883 7240
7520 20603 26.0 9916 7242
7440 20710 27.7 9888 7242
7450 20629 27.0 9904 7241
7340 20482 29.0 9916 7230
7310 20909 27.2 9510 7242
7450 20601 26.4 9918 7245
7325 20908 31.0 9923 7205
7500 20829 31.0 9894 7241
7070 20733 27.3 9954 7256
7200 20696 27.7 9920 7257
6560 20514 35.1 9935 7258
6980 20363 29.3 9913 7248
6700 20428 33.0 9941 7434
6520 20701 32.3 10061 7220
7780 20583 27.2 9931 7248
6800 20337 30.4 9928 7245
6910 20350 34.0 9954 7244
7030 20304 30.6 9899 7246
7070 20310 30.1 9932 7251
a) Prepare a scatter plot showing the relationship between the viscosity and each of the independent variables.

b) If the engineer wanted to build a regression model using only one independent variable to predict viscosity, which variable should be used?

c) Do you think this is an acceptable model?

d) Which independent variables should be included in the best model the engineer can develop?

e) Based on your best model, what should the engineer expect the viscosity to be with a batch that has a cellulose quality of 20,000, a fiber length of 30.0, 9900 lbs. of cellulose in the batch, and 7500 lbs. of EO in the batch?