The fill volume of soft-drink beverage bottles is an important quality characteristic. The volume is measured (approximately) by placing a gauge over the crown and comparing the height of the liquid in the neck of the bottle against a coded scale. On this scale, a reading of zero corresponds to the correct fill height. Fifteen samples of varying sizes have been analyzed, and the fill heights are shown in the following table. Subgroups 1, 2, and 3 are of size 10; subgroups 4, 5, and 6 are of size 5; subgroups 7, 8, 9, and 10 are of size 8; and subgroups 12, 13, 14, and 15 are of size 6.