New fertilizer compounds are often advertised with the promise of increased crop yields. Suppose we want to compare the mean yield μ₁ of wheat when a new fertilizer is used with the mean yield μ₂ with a fertilizer in common use. The estimate of the difference in mean yield per acre is to be correct to within .25 bushel with a confidence coefficient of .95. If the sample sizes are to be equal, find n₁ = n₂ = n, the number of 1-acre plots of wheat assigned to each fertilizer.