Exhibit 4-1
a Hospital Emergency Room Requires Different Numbers of Nurses

Exhibit 4-1
A hospital emergency room requires different numbers of nurses on different days of the week. The number of full-time employees required to be working (i.e. not on call) each day is given in the table below.
$\begin{array}{|l|l|l|l|l|l|l|}\hline \text { Mon } & \text { Tue } & \text { Wed } & \text { Thu } & \text { Fri } & \text { Sat } & \text { Sun } \\\hline 18 & 15 & 12 & 13 & 20 & 28 & 22\\\hline \end{array}$ Hospital rules require that nurses work four consecutive days, are on call for one day, and then receive two days off. The hospital wants to meet its daily requirements, while minimizing the number of nurses that must be on staff.
-Refer to Exhibit 4-1.Suppose the hospital has 40 nurses and is not allowed to hire or fire any employees,and cannot temporarily schedule nurses on their on call days.Determine a schedule that maximizes the number of weekend days off received by the nurses.