Bert’s Beachside Burgers is mostly a summer weekend business, but Bert opens for special events throughout the year, such as the New Year’s polar bear swim. The business has a fiscal year ending on December 31. It sells one kind of burger, which is purchased frozen. On January 1, Bert’s had 210 units in inventory with a cost of $3.20 each. During the year, 840 units were sold. Bert’s Beachside Burgers uses a periodic inventory system.