Suppose that you wish to test H₀: l₁ = l₂ versus H₁: μ₁ ≠ μ₂, where σ²₁ and σ²₂ are known. The total sample size N is to be determined, and the allocation of observations to the two populations such that n₁ + n₁ = N is to be made on the basis of cost. If the cost of sampling for populations 1 and 2 are C₁ and C₂, respectively, find the minimum cost sample sizes that provide a specified variance for the difference in sample means.