30 inventory purchases and sales

Inventory purchase and sales data are as follows. [Note: There was no inventory before the purchase made on January 1.] Purchased on January 1 -- 300 units, $9 cost per unit Purchased on January 16 -- 600 units, $10 cost per unit Purchased on January 25 -- 400 units, $6 cost per unit Sold on January 31 -- 500 units, $15 selling price per unit Assume that the company uses LIFO. Compute GROSS MARGIN for January. O $2,700 O $4,700 O $4,900 O $4,100 O $7,700 O $3,700 O $3,000 O $4,500