1. Pental Corporation has the following inventory records for October 2023. Operating expenses for the month of October were $500 and the 250 units sold generated Sales Revenue of $3,750.

Date	Item	Quantity (Units)	Unit Cost
Oct.1/23	Opening inventory	100	$9
Oct.7/23	Purchase	60	$9
Oct.10/23	Purchase	140	$10
Oct.19/23	Sales	250
Oct.22/23	Purchase	90	$11
Oct.28/23	Sales	50

What is the COGS and ending inventory, according to the:

1. Periodic inventory systems, assuming FIFO is used.
2. Perpetual inventory system, assuming that FIFO is used.

Please clearly show the calculations

I have personally tried the solution for question 1 below, but it seems my answer is wrong.

My Solution: For question 1

Units Cost per unit

Oct 1/23 Opening Inv. 100 $9

Oct 7/23 Purchase 60 $9

Oct 10/23 Purchase 140 $10

Oct 19/23 Sale 250 (100 x $9) $900

(60 x $9) $540

(140 x $10) $1,400

Oct 22/23 Purchase 90 $11

Oct 28/23 Sale 50 (50 x $11) $550

Ending inv. = 900 + 540+ 1,400 + (900) + (540) + (1,400) + 990 + (550) = 440

COGS = 900 + 540 + 1400+ 550 = 3390

Can you please tell me where i went wrong, thank you!