Sheiffeld Bookstore had 550 units on hand at January 1, costing $9 each. Purchases and sales during the month of January were as follows: Shetfield does not maintain perpetual irventory records. According to a plysical count, 360 units were on hand at January 31. The cost of the imventoryat January 31 , under the LifO method is: $3960$3240$4320$4110