An experiment was carried out to investigate the effect of species (factor a, with i = 4) and grade (factor b, with j = 3) on breaking strength of wood specimens. one observation was made for each species—grade combination—resulting in ssa = 449.0, ssb = 425.6, and sse = 127.4. assume that an additive model is appropriate. (a) test h0: α1 = α2 = α3 = α4 = 0 (no differences in true average strength due to species) versus ha: at least one αi ≠ 0 using a level 0.05 test. calculate the test statistic. (round your answer to two decimal places.) f =