Use the following problem statement to answer questions 1-6. A hospital wants to determine the nursing schedule. Their staff consist of full-time nurses who work eight-hour shifts and part-time nurses who work four-hour shifts. The supervisor of nurses divides the day into six four-hour periods. In each period, a different level of demand (number of cases to be treated) requires different numbers of nurses to hire. The minimum number of nurses required is shown in Table 1. It is also required that there must be at least 3 full-time nurses at each time period. The full-time nurses get paid $140 per shift while the part-time nurses get paid $60 per shift. The normal shifts can begin at the start of any of the four-hour periods. The hospital wants to minimize total cost. Formulate a model. [Note: Xi = no. of full-time nurses beginning their shift at time period i, where i = 1, 2, 3, 4, 5, and 6. Yi = no. of part-time nurses beginning their shift at time period i, where i = 1, 2, 3, 4, 5, and 6.] -------------------------------------------------------------------------- Time Period Min. number of nurses needed -------------------------------------------------------------------------- 1. 7:00 AM - 11:00 AM: 22 2. 11:00 AM - 3:00 PM: 18 3. 3:00 PM - 7:00 PM: 19 4. 7:00 PM - 11:00 PM: 21 5. 11:00 PM - 3:00 AM: 16 6. 3:00 AM - 7:00 AM: 15 -------------------------------------------------------------------------- Which of the following objective functions is correct?

Group of answer choices:

Min Z = 140 (X1 + X2 + X3 + X4 + X5 + X6) + 60 (Y1 + Y2 + Y3 + Y4 + Y5 + Y6)

Min Z 140 (X1 + X2 + X3 + X4 + X5 + X6) + 60 (Y1 + Y2 + Y3 + Y4 + Y5 + Y6)

Max Z = 140 (X1 + X2 + X3 + X4 + X5 + X6) + 60 (Y1 + Y2 + Y3 + Y4 + Y5 + Y6)