Sales for January = 50,000 units
Sales for February = January sales + 4 % of January sales = 50,000 units + 4 % * 50,000 units
Sales for February = 52,000 units
Total units needed to be purchased in February = Sales for February + Ending inventory - Beginning Inventory
Ending inventory = 10,000 units
Beginning inventory = 10,000 units
Total units needed to be purchased in February = 52,000 units + 10,000 units - 10,000 units
Total units needed to be purchased in February = 52,000 units