Snookers Restaurant is open from 7 am to 10:00 pm Monday to Sunday. Besides the hours that they are open for business, workers are needed an hour before opening and an hour after closing for setup and cleanup activities. The restaurant operates with both fulltime and part-time workers on the following shifts:
Shift Daily pay rate
6:00 am – 10:00 pm $40
6:00 am - 2:00 pm $80
10:00 am – 2:00 pm $40
10:00 am – 6:00 pm $80
2:00 pm – 6:00 pm $40
2:00 pm – 10:00 pm $80
The following numbers of workers are needed during each of the indicated time blocks.
Hours Workers needed
6:00 am – 10:00 am 9
10:00 am – 1:00 pm 18
1:00 pm – 4:00 pm 11
4:00 pm – 7:00 pm 16
7:00 pm – 11:00 pm 5
At least one full-time worker must be available during the hour before opening and after closing. Additionally, at least 20% of the employees should be full-time (8-hour) workers during the restaurant’s busy periods from 10:00 am–1:00 pm and 4:00 pm–7:00 pm.
a) Formulate an ILP for this problem with the objective of minimizing total daily labor costs.
b) Implement your model in a spreadsheet and solve it.
c) What is the optimal solution for this problem?