The director, as often as he deems advisable, shall weigh, measure or inspect packages or amounts of commodities offered or exposed for sale, sold, or in the process of delivery, to determine whether they contain the amounts represented and whether they be offered or exposed for sale, or sold in accordance with law. When such packages or amounts of commodities are found not to contain the amounts represented, or are found to be kept, or offered or exposed for sale in violation of law, the director may order their sale discontinued and may so mark or tag them as to show them to be illegal. The director may employ recognized sampling procedures under which the compliance of a given lot of packages will be determined on the basis of the result obtained on a sample selected from and representative of such lot.