To decide whether chemistry or physics majors have higher starting salaries in industry, n B.S. graduates of each type are surveyed, yielding x̅ = $61;500 for chemistry and y̅ = $61;000 for physics. Assume σ = $2500 for both populations. 

Calculate the P-value for the appropriate two sample z test, assuming that the data was based on n = 100. Then repeat the calculation for n = 400. Is the small P-value for n = 400 indicative of a difference that has practical significance? Would you have been satisfied with just a report of the P-value? Comment briefly.