1. (15 points) On 31 December 2020, a protective mask factory should plan and decide the amount of protective masks to be produced and the related workforce level for the first half year in 2021. The following table shows the production days and predicted demand in the future 6 months: Month Jan Feb Production Days 25 Predicted demand (in thousand units) 400 20 250 22 Mar Apr May Jun 24 18 16 340 210 240 150 The factory possesses 120 thousand masks in stock and 40 labors at the end of 2020. On average, 200 labors can produce 900 thousand masks in 30 days. The inventory holding cost rate is $0.3/mask/year. The cost of hiring a new labor is $350 and firing a labor is $500. By using the Level Strategy, fill in the table below and determine the total cost, including: inventory holding cost, hiring cost, and firing cost, of the next 6 month. Month Jan Feb Mar Apr May Jun Net predicted demand Cumulative net predicted demand Number of units produced per worker Cumulative number of units produced per worker Ratio Number of workers required Number of workers hired Number of workers fired Production units Cumulative production Ending Inventory