Harper Water Ltd was established on 2 January 2021. The company sells water purifier machines and uses the perpetual inventory system. The company started with 100 water purifier machines that cost $600 each. On 15 January 2021, the company bought another 100 machines that cost $500 each. During January 2021, the company sold 120 machines. The first sale of 40 machines was made on 10 January. The second sale of 80 machines was made on 20 January. All the machines were sold at $1,500 each. (a) Present the ending inventory cost, cost of goods sold and gross profit for January 2021 under: (i) FIFO method (10 marks) (ii) Weighted average method (10 marks) (b) Explain the effects of the weighted-average method on the value of ending inventory and gross profit for January 2021. (10 marks)