An algorithm for determining the lower confidence limit (NDH) for the minimum value of the hardness of a set of machine parts by calculation is developed. For processing of statistical data of the hardness measurements used a three-parameter Weibull distribution is offered. The transition from sample data to population data is carried out by the graphical method. According to the algorithm, NDH was found for the minimum hardness value with confidence probabilities p=0.9; 0.92;0.93;0.94.

Keywords: hardness, machine parts, sampling, aggregate, lower confidence limit, graphic method, calculation method

The analytical method determination parameters of the three-parametrical Waybill distribution for final volume population on the basis received parameters on a sample is stated in this work The algorithm of calculation on which computing experiment is made is presented. On the basis of these calculations the conclusion that it is necessary to determine by this analytical method parameters of the three-parametrical law of Waybill for set of final volume on the basis of the received parameters on a sample is drawn.

Keywords: population of final volume, sample, dispersion, an average quadratic deviation, distribution parameters, durability became