SeCo begins operations in 20X6 and uses the periodic method and weighted-average costing. SeCo has the following merchandise purchases during 20X6: 700 units in March @ $4; 1,100 units in July@$6; and 2,200 units in October $7. A physical count of ending inventory finds 1,000 units. Calculate the cost of goods sold 16. a. $6,200 b. $7,000 c. $18,600 d. $24,000