Average days in Inventory. FIFO

Hello v-juanli-msft 

Every cell has a different formula because I want to determine the age of the inventory taking into account the order in which the product(s) entered. Is the same thing as if I buy a product in different dates and the selling price of the product is different. On sheet2 of the following link I've created an example doing what I want to do but instead of using dates I used price. In column F you can see the formulas I used. Just like the previous example there's in not a constant formula because it depends on the date the product was bought. 

https://drive.google.com/open?id=1yFP0WlZkJE2USgeRYWuHevMGZ7q0sJn4maEY4c2OYC4

Thanks,