Montoure Company uses a perpetual inventory system. It entered into the following calendar$-$year purchases and sales transactions.

The company's manager earns a bonus based on a percent of gross profit. Which method of inventory costing produces the

highest bonus for the manager?

Compute cost of goods available for sale and the number of units available for sale.

Compute the number of units in ending inventory.

Compute the cost assigned to ending inventory using specific identification. $($For specific identification, units sold consist of $660$ units from beginning inventory, $230$ from the February $10$ purchase, $110$ from the March $13$ purchase, $130$ from the August $21$ purchase, and $380$ from the September $5$ purchase.$)$

Compute gross profit earned by the company for each of the four costing methods.

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