FIFO Accounting Question

Carstow uses the perpetual inventory method. Carstow had the following inventory transactions in May, 2001, On May 1, Carstow had 250 units in inventory that cost $8 each. On May 14, Carstow purchased 800 units at $10 each. On May 20, Carstow purchased 60 units at $13 each. On May 24, Carstow purchased 110 units at $14 each. Carstow sold 840 units during May for $28 each. What is the cost of Carstow's inventory at the end of May assuming Carstow uses the FIFO method?

*FIFO COGS = $7900 (I tried this and it was incorrect?)

Is it asking for total COGS? I only have 1 attempt left so I need confirmation. Thanks!