(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 Q921 and one Q239. The QR432 assembly consists of three P456, one R478 and two S590. (i) Prepare a Bill of Material (BOM) product tree for the product PQR345. (ii) 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.

Table Q3(b)-1
Week		10			11		12			13		14			15	16
PQR345		70			50		120			60		90			100	40
QR432		100			-		-			250		-			150	100

Table Q3(b)-2
Item	Lead Time (Weeks)			On Hand		Batch Size		Safety Stock
PQR345	1			200		200		0
QR432	2			200		300		150
S590	2			700		600		350