Periodic Inventory by Three Methods Dymac Appliances uses the periodic inventory system. Details regarding the inventory of appliances at January 1, purchases invoices during the next 12 months, and the inventory count at December 31 are summarized as follows: Purchases Invoices Model Inventory, January 1 Inventory Count, 1st 2nd 3rd December 31 A10 4 at $ 28 4 at $ 31 4 at $ 34 5 B15 8 at $ 91 4 at 32 82 3 at 88 6 at 95 7 E60 3 at 65 3 at 55 15 at 58 9 at 60 60 5 G83 7 at 232 6 at 240 5 at 250 10 at 249 9 J34 12 at 68 10 at 70 16 at 77 16 at 78 13 M90 2 at 115 2 at 117 3 at 135 3 at 137 Q70 5 at 167 4 at 177 4 at 182 7 at 187 58