Final answer:
The optimal order quantity that minimizes inventory costs is 30 units.
Step-by-step explanation:
To determine the optimal order quantity that minimizes inventory costs, we need to calculate the Economic Order Quantity (EOQ). The EOQ formula is:
EOQ = sqrt((2 * demand * ordering cost) / holding cost)
Given that the weekly demand is 20, the ordering cost is $120, and the holding cost is 25% of the price paid ($7.50).
Plugging in these values into the EOQ formula:
EOQ = sqrt((2 * 20 * 120) / 7.50) ≈ 30
Rounding to the nearest whole number, the optimal order quantity that minimizes inventory costs is 30 units.