only need to understand the chase demand production plan, thanks

7. Chapman Pharmaceuticals, a large manufacturer of drugs, has this aggregate demand forecast (in thousands of liters) for a liquid cold medicine. The firm has a normal production rate of 90 thousand liters per month, and the initial inventory is 100 thousand liters. Inventory holding costs are $30 per 1,000 liters per month, regular-time production costs are $400 per 1,000 liters. Overtime costs an additional 20 percent, and undertime costs an additional 11%. Assume that there are no lost sales or rate change costs. Compute and compare the total cost of a level production rate of 100 thousand liters per month and a chase demand production plan. (20 Points)