An article in the Journal of Quality Technology describes and experiment that investigates the effects of four bleaching chemicals on pulp brightness. These four chemicals were selected at random from a large population of potential bleaching agents. The data are as follows:

Chemical Pulp Brightness
1 77.199 74.466 92.746 76.208 82.876
2 80.522 79.306 81.914 80.346 73.385
3 79.417 78.017 91.596 80.802 80.626
4 78.001 78.358 77.544 77.364 77.386

a. Is there a difference in the chemical types. Use α = 0.05.
b. Estimate the variability due to chemical types.
c. Estimate the variability due to random error.