The units of an item available for sale during the year were as follows:

Jan. $10$ ?Inventory $27$ ?units @ $$90$

Feb. $27$ ?Purchase $54$ ?units $$$98$

July $11$ ?Purchase $63$ ?units $$106$

Nov. $13$ ?Purchase $36$ ?units @ $$115$

There are $50$ ?units of the item in the physical inventory at December $31.$ ?The periodic inventory system is used.

a$.$ ?Determine the ending inventory cost using the first$-$in$,$ ?first$-$out method.

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b$.$ ?Determine the ending inventory cost using the last$-$in$,$ ?first$-$out method.

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c$.$ ?Determine the ending inventory cost using the weighted average cost method.