=+c. Given that catalyst ratio, curing temperature, and curing time all remain in the model, do you think that formaldehyde concentration provides useful information about durable press rating?

Data for Exercise 66 Obs Formaldehyde concentration Catalyst ratio Curing temperature Curing time Durable press rating 1 8 4 100 1 1.4 2 2 4 180 7 2.2 3 7 4 180 1 4.6 4 10 7 120 5 4.9 5 7 4 180 5 4.6