The present article refers directly to the papers [1] and [2]. At first a specified model from [1] is shortly presented, which then is solved in closed form by means of results given in [2]. This requires a short summary of some theoretical results, too. The essential result of the paper consists in the fact, that it is possible here, to solve in form of analytical expressions a practical problem, where the dependence on all process parameters is on served, by making use of dynamical programming.