Acompany manufactures two types of hand calculators, model c1 and model c2. it takes 1 hour and 4 hours in labor time to manufacture each c1 and c2, respectively. the cost of manufacturing the c1 is $30 and that of manufacturing a c2 is $20. the company has 1,600 hours of labor time available and $18,000 in running costs. the profit on each c1 is $10 and on each c2 is $9. what should the production schedule be to ensure maximum profit?