3. An air-conditioning and refrigeration company has been awarded a contract for the airconditioning of a new computer installation. The company has to make a choice between two alternatives:

(a) hire one or more refrigeration technicians for 6 hours a day, or

(b) hire one or more part time refrigeration apprentice technicians for 4 hours a day.

The rate of wages of the refrigeration technicians is Rs 20 per hour, while the corresponding rate for apprentice technicians is Rs 8 per hour. The company wants to engage the technicians on work for not more than 25 man-hours per day and also limit the charges to technicians to Rs 240. The company estimates that the productivity of a refrigeration technician is 8 units and that of a part-time apprentice technician is 3 units. Formulate the integer programming problem to enable the company to select the optimum number of technicians and apprentices.