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(b) Salalah Electro-Mechanical Company manufactures a product PQR345. The product PQR345 consists of two PQ890 assemblies, three QR432 assemblies and one PR678 assembly. The PQ890 assembly consists of one P456, two 0921 and one Q239. The QR432 assembly consists of three P456, one R478 and two S590. Prepare a Bill of Material (BOM) product tree for the product PQR345. [2] () Using Table Q3(b)-1 and Table Q3(b)-2 complete the Material Requirements Planning (MRP) calculations to determine when the Purchase Orders should be placed for item S590. Note: The product PQR345 are being sold complete as well as the spare parts (e.g. items QR432, PQ890, R478 etc) are being sold separately also. [4] Week PQR345 QR432 10 70 100 11 50 Table Q3(b)-1 12 120 13 60 250 14 90 15 100 150 16 40 100 Table Q3(b)-2 Item Lead Time (Weeks) On Hand Batch Size Safety Stock PQR345 QR432 S590 300 300 800 200 300 2 0 150 350 2 600 [Total 16 marks)