At a distribution center, terminal docks include casual workers who are hired temporarily to account for peak loads. The minimum demand for casual workers during the seven days of the week (starting on Monday) is 18, 20, 15, 10, 18, 12, 10 workers. Each worker is contracted to work three consecutive days (consequently, Friday is the last day of the week in which new workers can be hired).

Formulate a mathematical program to determine the optimal weekly hiring practice of casual workers for the company using the appropriate formulation (e.g., LP, IP, MIP, or NLP) and explain why you chose the formulation you chose.