Topanga Group began operations early in 2021. Inventory purchase information for the quarter ended March 31, 2021, for Topanga's only product is provided below. The unit costs include the cost of freight. The company uses a periodic inventory system to report inventory and cost of goods sold. Date of Purchase Units Unit Cost Total Cost Jan. 7 5,000 $4.00 $ 20,000 Feb. 16 12.000 4.50 54,000 March 22 17.000 5.00 85,000 Total purchases 34.000 $ 159,000 Sales for the quarter, all at $7.00 per unit, totaled 20,000 units leaving 14,000 units on hand at the end of the quarter. Required: 1. Calculate Topanga's gross profit ratio for the first quarter using: a. FIFO b. LIFO c. Average cost 2. Comment on the relative effect of each of the three inventory methods on the gross profit ratio