Формула 5: S = ∑ᵢ₌₁ᵐ Sᵢ(1 + ptᵢ/K) + ∑ᵢ₌ₘ₊₁ⁿ Sᵢ(1 + ptᵢ/K)⁻¹.

\(S=\displaystyle\sum_{i=1}^{m}S_i\left(1+\frac{pt_i}{K}\right)+\sum_{i=m+1}^{n}S_i\left(1+\frac{pt_i}{K}\right)^{-1}\)