In book it is written that “Acceptable Quality Limit (AQL) is the point at (up to) which the customer will have to definitely accept the lot and Lot Tolerance Percent Defective (LTPD) is the point at (after) which the customer will definitely reject the lot.” My question is how the customers can come to know about the proportion defective in the lot because they are only doing the testing for the samples, not for the whole lot?