3. Mehmet is the officer of the customer service center and he is assigned to schedule the workers required in different time periods. The center is open between 7am-3pm. Mehmet has monitored the usage intensity of the center at different time periods of the day and decided that the minimum numbers of workers should be 8, 16, 20, and 12 for shift 1 (7am-9am), shift 2 (9am-11am), shift 3 (11am-1pm), and shift 4 (1pm-3pm), respectively. In order to meet the requirements in the center, two types of workers can be hired: type-I and type- II. Type-I workers should work 2 consecutive shifts (4 hours), thus, they can start work in any of shift 1, shift 2, and shift 3. Type-I workers are paid $7 per hour. On the other hand, type-II workers can start work in any of the four shifts and are paid $6 per hour. Mehmet wants the following condition during every time period: for each type-II worker in any shift, there must be at least one type-I worker. He would like to determine how many type-I and type-II workers should be hired to meet the above requirements at the minimum possible cost. Formulate an LP model for this