12-9. To compare the durabilities of two premium exterior house paints (one from House Depot and the other sold by KK-Mart), nine 4 × 6 panels of each paint were exposed to the elements for a six-month trial period.

(The arrangement of the panels was randomly determined.) At the end of the trial period the following reflectivity readings were obtained (higher values represent greater reflectivity):

HD: 9.6, 11.1, 11.6, 9.8, 8.9, 9.5, 10.2, 11.5, 10.1 KK-Mart: 9.4, 10.1, 9.2, 8.0, 10.1, 10.6, 7.2, 8.5, 9.5 For α = 0.05, determine if the paints exhibit equal reflectivity. What sampling assumptions are being made?