I will be grateful for your help on finding my error. I am attaching the image with an exercise description, and an excel file, in which I computed COGS and the required Gross Profit. This is a tiny exercise.
I don't understand why my COGS under FIFO are incorrect (shall be 312,900.00, but my one is 308,000.00), and thus yield the incorrect Gross Profit, while both COGS and Gross Profit under LIFO are correct.
Thank you very much!