H0: μ = 8
H1: μ > 8
t = (8.25 - 8)/(0.8/sqrt(28)) = 1.654
t_table = 1.703
since t_calc < t_table, we accept H0, and conclude that the sample does not provide cnvincing evidence that the fertilizer had a positive impact on the weight of the corn ears at 0.05 level of significant.