As part of the multi lab study, four fabrics are tested for flammability at the National Bureau of Standards. The following burn times in seconds are recorded after a paper tab is ignited on the hem of a dress made of each fabric.

(a) State the statistical model and present the ANOVA table. With a = .05, test the null hypothesis of no difference in the degree of flammability for the four fabrics.
(b) If the null hypothesis is rejected, construct simultaneous confidence intervals to determine the fabric(s) with the lowest mean burn time.
(c) Plot the residuals and comment on the plausibility of the assumptions.
(d) If the tests had been conducted one at a time on a single mannequin, how would you have randomized the fabrics tested in this experiment?

Fabric Fabri2 Fabric3 Fabric 4 17.8 16.2 17.5 174 15.0 11.2 1.8 110 10.0 9.2 9.2 14.9 15.8 100 104 10.7 10.7