There are 10,000 units in stock for the beginning of January, and maximum inventory holding is 19,000 units. Sales are recorded at the end of the month.

Procurement receives a communication from one of its retailers that it is planning a promotional event in July. The retailer forecasts that it will require an additional 20,000 units. By how much should the level production strategy increase its monthly output of units in order to meet the requirements of the retailer and minimize overall inventory levels?