The inventory records for Radford Co. reflected the following Beginning inventory@May 1 100 units $4.00 First purchase@May 7 Second purchase @May 17 Third purchase @ May 23 Sales@ May 31 300 units@ $4.40 500 units $4.60 100 units $4.80 900 units $7.80 13. Determine the amount of cost of goods sold assuming the LIFO cost flow method. A. $4,100 B. $4,320 C. $2,360 D. $3,600 15. Determine the amount of gross margin assuming the weighted average cost flow method. A. $3,015 B. $2,412 C. $1,314 D. $2970