Cantik Selesa is a retail phone-catalogue company that specializes in casual wear and accessories. A phone station at the company will be staffed with either full-time operators or temporary operators 8 hours per day. Full-time operators, because of their experience and training, process more orders and make fewer mistakes than temporary operators. However temporary operators are cheaper because they receive a lower wage rate and are not paid benefits. A full-time operator can process about 360 orders per week, whereas a temporary operator can process about 270 orders per week. A full-time operator averages 1.1 defective orders per week, and a part-time operator incurs about 2.7 defective orders per week. The company wants to limit defective orders to 200 per week. The cost of staffing a station with full-time operators is RM610 per week, and the cost of a station with part-time operators is RM450 per week. Using historical data and forecasting techniques, the company has developed estimates of phone orders for an 8-week period, as follows:

Week Order

1 19,500

2 21,000

3 25,600

4 27,200

5 33,400

6 29,800

7 27,000

8 31,000

The company does not want to hire or dismiss full-time employees after the first week (the company wants a constant group of full-time operators over the 8-week period). The company wants to determine how many full-time operators it needs and how many temporary operators to hire each week to meet weekly demand while minimizing labour costs.

a. Formulate a linear programming model for this problem

b. Solve this model using Excel.