4. (Total 25 points) It is given that K and L are the immediate upper level items for P in the product structure (BOM) and each unit of K needs 6 units of P and each unit of L needs 3 units of P. P is not required by any other items in the product structure. Given the following planned order release (PRL) for K and L, obtain the gross requirements (GR) for P and then obtain PRL for P in the MRP table if P has a scheduled receipt of 150 in period 1 and 400 in period 6, and on-hand inventory of 900 units. The lead times for K, L, and P are 1, 1, and 2 periods respectively. Periods 4 5 6 1 2 3 K: LT= PRL 7 120 100 100 90 75 L: LT= PRL 110 120 80 70 P: LT= GR SR OH NR POR PRL 7 points for obtaining GR of P in different periods 18 points for obtaining the rest of the values in the table for p in different periods