Sheffield Bookstore had 550 units on hand at January 1, costing $9 each. Purchases and sales during the month of January follows: Purchases Date Jan. 14 17 Sales 370 @ $13 210 @ $12 210 @ $11 25 29 240 @ $15 Sheffield does not maintain perpetual inventory records. According to a physical count, 360 units were on hand at January 31. The cost of the inventory at January 31, under the LIFO method is: $4320 $3960 $4110 $3240