1. A purchasing department sends out about 100 routine orders a day. Each person in the department can deal with three orders an hour, but has to do associated paperwork that takes an average of 40 minutes an order. Each person also loses about 20% of their time doing other things. The standard working day is from 0900 to 1600 five days a week, with an hour off for lunch. How many employees do you think the department should employ? 2. Sean Higgins estimates that his periodic plant maintenance costs g50,000. If he does not close the plant and do this maintenance, his breakdown costs rise as shown below. How often should he maintain the plant? Time since last maintenance (years) 0 1 2 3 4 5 Annual cost of breakdowns (g000) 0 10 40 80 150 240 3. A warehouse has to meet the demand for a product shown below. Each unit of stock remaining at the end of a month has a notional holding cost of £20. If there are shortages, 20% of orders are lost at a cost of £200 a unit, and the rest are met by back orders, at a cost of £50 a unit. A production department sends the product to the warehouse. Designed capacity of this department is 400 units a month, but utilisation seldom exceeds 80%. Every time the production rate is changed it costs £15,000. How would you set about designing an aggregate plan for the product? Month 1 2 3 4 5 6 7 8 Aggregate demand 310 280 260 300 360 250 160 100
2. . Eight jobs are to be processed on a single machine, with processing times as follows: Job A B C D E F G H Processing time 2 5 3 8 4 7 2 3 Due date 13 7 8 30 14 20 2 36 How could you design short-term schedules for the jobs?
3. . Eight jobs are to be processed on a single machine, with processing times as follows:
4. Job A B C D E F G H
5. Processing time 2 5 3 8 4 7 2 3
6. Due date 13 7 8 30 14 20 2 36
7. How could you design short-term schedules for the jobs?