21 Shoemakers of America forecasts the following demand for each of the next six months: month 1—5,000 pairs;

month 2—6,000 pairs; month 3—5,000 pairs; month 4—

9,000 pairs; month 5—6,000 pairs; month 6—5,000 pairs. It takes a shoemaker 15 minutes to produce a pair of shoes.

Each shoemaker works 150 hours per month plus up to 40 hours per month of overtime. A shoemaker is paid a regular salary of $2,000 per month plus $50 per hour for overtime.

At the beginning of each month, Shoemakers can either hire or fire workers. It costs the company $1,500 to hire a worker and $1,900 to fire a worker. The monthly holding cost per pair of shoes is 3% of the cost of producing a pair of shoes with regular-time labor. (The raw materials in a pair of shoes cost $10.) Formulate an LP that minimizes the cost of meeting (on time) the demands of the next six months. At the beginning of month 1, Shoemakers has 13 workers.