Shin Company sells one product. Presented below is information for January for Shin Company.
Jan. 1 Inventory ..... 300 units at $10 each
4 Sale ......... 240 units at $16 each
11 Purchase ........ 450 units at $12 each
13 Sale .......... 360 units at $17.50 each
20 Purchase ......... 480 units at $14 each
27 Sale .......... 300 units at $18 each
Shin uses the FIFO cost flow assumption. All purchases and sales are on account.

Instructions
(a) Assume Shin uses a periodic system. Prepare all necessary journal entries, including the end-of-month closing entry to record cost of goods sold. A physical count indicates that the ending inventory for January is 330 units.
(b) Compute gross profit using the periodic system.
(c) Assume Shin uses a perpetual system. Prepare all necessary journal entries.
(d) Compute gross profit using the perpetual system.