A record of transactions for the month of May was as follows:

Purchases :

Beg Balance 600 @ $5.00 = $3,000

May 4 900 @ $5.20 = $4,680

8 600 @ $5.10 = $3,060

14 1,100 @ $5.30 = $5,830

Sales:

May 3 300 @ $8.00

6 1,000 @ 8.00

12 800 @ 8.00

18 400 @ 8.00

a) Calculate the ending inventory balance using LIFO.

b) If the company had used FIFO, what would have been the gross profit ratio reported for May?

c) If the company had used average costing instead of FIFO, by how much would Mays cost of goods sold differ? (be sure to indicate the amount and whether that amount is higher or lower)