The accounting records of Amp Electronics show the following data.

Beginning inventory	4,000 units at $5
Purchases	7,000 units at $7
Sales	9,400 units at $10

Determine cost of goods sold during the period under a periodic inventory system using (a) the FIFO method, (b) the LIFO method, and (c) the average-cost method. (Round unit cost to three decimal places.) Show work.