Please explain part (b) and the Solver parameters (specifically which to set as binary) to produce the correct solution of:

Min (Z) = X1 + X2 + X3 + X4 + X5 + X6 + X7 = 5 + 2 + 6 + 2 + 6 + 2 + 1 =24

I'm getting the incorrect answer with Solver parameters set as:

10. Garden City Beach is a popular summer vacation destination for thousands of people. Each summer, the city hires temporary lifeguards to ensure the safety of the vacationing public. Garden City's lifeguards are assigned to work five consecutive days each week and then have two days off. However, the city's insurance company requires them to have at least the following number of lifeguards on duty each day of the week: + Minimum Number of Lifeguards Required Each Day Monday Tuesday Wednesday Thursday Sunday Friday Lifeguards 18 17 16 16 16 14 The city manager would like to determine the minimum number of lifeguards that will have to be hired. a. Formulate an ILP for this problem. b. Implement your model in a spreadsheet and solve it. c. What is the optimal solution? d. Several lifeguards have expressed a preference to be off on Saturdays and Sundays. What is the maximum number of lifeguards that can be off on the weekend without increasing the total number of life guards required? Sunday 18 Minimum Number of Lifeguards Required Each Day Monday Tuesday Wednesday Thursday Friday 17 16 16 16 14 Saturday 19 Lifeguards Solver Parameters Set Objective: $1$39 To: O Max O Min O Value of: 0 By Changing Variable Cells: $1$29:SI$35 1 Subject to the Constraints: $B$36:SH$36 >= $B$37:SH$37 SI$29:$1$35 >= 0 Add Change Delete Reset All Load/Save Make Unconstrained variables Non-Negative Select a Solving Method: Simplex LP Options Solving Method Select the GRG Nonlinear engine for Solver Problems that are smooth nonlinear. Select the LP Simplex engine for linear Solver Problems, and select the Evolutionary engine for Solver problems that are non-smooth. Help Solve Close X1 X3 Shift 1 an X4 1 X5 1 1 X6 1 Lifeguards Scheduled 5 2 5 2 X2 0 0 1 1 1 1 1 1 1 2 6 3 nin X7 1 1 1 1 1 1 1 1 0 0 1 Nm OOHHHH9 6 2 6 NN NU NN 1 1 1 0 0 1 1 5 6 7 Available Required 1 2 6 2 1 4 28 29 30 31 32 33 34 35 36 37 38 39 20 1 12 13 1 OOPS HO.99 1 1 16 16 Oo99 18 1 16 16 17 17 16 16 14 14 19 19 18 Total Lifeguards 23 18 17 16 16 16 LE 21