Your question is Warehouse Inventory System with FIFO. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Design a warehouse inventory system that receives and delivers stock while tracking quantity on hand, inventory value and average unit cost; then extend it to FIFO costing where deliveries consume the oldest receipts first, including partial batch consumption.
Asked in the Technical interview stage. Two-part; candidate used a queue of receipts. Reported follow-ups: Switch from average cost to FIFO costing; Handle partially consumed batches.