auditing question

The following are sales, cost of sales, and inventory data for Kids' Tent distributor of toys and learning products for kids. Sales COGS 2021 2020 82,800,000.00 76,800,000.00 58,400,000.00 57,200,000.00 8,200,000.00 7,400,000.00 10,600,000.00 8,200,000.00 2019 2018 68,400,000.00 59,600,000.00 50,800,000.00 44,000,000.00 6,600,000.00 5,000,000.00 7,400,000.00 6,600,000.00 Beginning Inventory Ending inventory Required: a. Calculate the following ratios: (4 Marks ) (1) Gross margin as a percentage of sales (2) Inventory turnover b. List several logical causes of the changes in the two ratios.(at least 2 causes for each ratio). (2 Marks) C. Assume that $2,000,000 is considered material for audit planning purposes for 2021. Do any of the fluctuations in the computed ratios indicate a possible material misstatement? (3 Marks) d. What should the auditor do to determine the actual cause of the changes?(1 Marks)