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Laker Company reported the following January purchases and sales data for its only product. For specific identification, ending inventory consists of $310$ units from the January $30$ purchase, $5$ units from the January $20$ purchase, and $30$ units from beginning inventory.

The Company uses a periodic inventory system. For specific identification, ending inventory consists of $310$ units from the January $30$ purchase, $5$ units from the January $20$ purchase, and $30$ units from beginning inventory. Determine the cost assigned to ending inventory and to cost of goods sold using

$($a$)$ specific identification,

$($b$)$ weighted average,

$($c$)$ FIFO, and

$($d$)$ LIFO.