Trey Monson starts a merchandising business on December $1$ and enters into the following three inventory purchases. Monson uses a perpetual inventory system. Also, on December $15,$ Monson sells $15$ units for $$39$ each.

Purchases on December $7,10$ units @ $$25\mathrm{.}00$ cost

Purchases on December $1420$ units @ $$31\mathrm{.}00$ cost

Purchases on December $21,15$ units @ $$33\mathrm{.}00$ cost

$1.$ Determine the costs assigned to the December $31$ ending inventory based on the FIFO method.

$2.$Determine the costs assigned to ending inventory when costs are assigned based on the LIFO method.

$3.$Determine the costs assigned to ending inventory when costs are assigned based on the weighted average method.

Note: Round your per unit costs to $2$ decimal places.

$4.$Of the units sold, $8$ are from the December $7$ purchase and $7$ are from the December $14$ purchase. Determine the costs assigned to ending inventory when costs are assigned based on specific identification.