The number of miles of useful tread wear (in 1000’s) was determined for tires of each of five different makes of subcompact car (factor A, with I = 5) in combination with each of four different brands of radial tires (factor B, with J = 4), resulting in IJ = 20 observations. The values SSA = 30.6, SSB = 44.1, and SSE = 59.2 were then computed. Assume that an additive model is appropriate.

a.

b.

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Test Ho: %1 = α₂ = α3 = α4 = α5 = 0 (no differences in true average tire life- time due to makes of cars) versus Ha: at least one ; 0 using a level .05 test.