Components Zelac corporation is a Coal manufacturing company use three components Tar, Sulphate, and Benzol as follows: Normal Usage Maximum Minimum Re-order Usage Re-order quantity Usage per week period per week per week Tar 2,000 Units 12,400 Units 1,300 Units 5 to 7 week 460 Units Sulphate 2,400 Units 16,000 Units 1200 Units 4to 6 week 400 Units Benzol 2,000 Units 23,200 Units 1,300 Units 6to 8 week 460 Units Calculate: (a) Re-order level (b) Minimum level (c) Maximum level (d) Average stock level