For effective management of industrial or commercial enterprise using a resource with limited period of validity it is necessary to have reliable appraisals of basic characteristics of casual process of employing this resource. These characteristics include mathematical expectations (average values) and dispersions of the following random values: volume of demands for a resource during production cycle X and time of using a lot of resource t. The result of the work of an enterprise can be achievement of statistical (selective) data of two types: 1) real time of using a lot of resource (if there isn’t enough resource), 2) real amount of employed resource (if there is some resource left).