Question $1)(25$ pt$.)$

A retall store sells $12000$ units of a product to its customers each year. They buy each unit from the supplier for $560$ and wait about $3$ days after placing the order for dellvery from the supplier. The setup cost for ordering this product is $$12$ per order, and the holding cost per unit per year is $5\%$ of the unit purchasing cost. $($Assume $200$ working days per vear.$)$ In order to minimize the total cost $($holding cost plus setup cost$)$:

A$)$ What is the optimal order quantity?

B$)$ How many orders should the store place per vear?

c$)$ What is the reorder point?

D$)$ What is the total annual cost $($holding cost $+$ ordering cost$)?$