Question:

Surfing Fun Limited imports surfboards and sells them to department stores throughout New Zealand. At $1$ July $2023$ opening inventory comprises $10$ units at $$22$ each. Throughout the quarter ended $30$ September $2023$ the sales price of surfboards was $$30.$ Extracts from the inventory record reveal the following transactions.

$\backslash$table$[[$Date$,$Purchases,Sales$],[31$ July,$20$ units at $$20,],[2$ August,,$5$ units$],[4$ August,,$16$ units$],[31$ August,$15$ units at $$18,],[3$ September,,$12$ units$],[10$ September,$10$ units at $$21,],[29$ September,,$11$ units$]]$

Required

Calculate the ending inventory and cost of sales for the quarter ending $30$ September $2023$ using FIFO, LIFO and Average cost methods, assuming that Surfing Fun Limited chooses the:

a$)$ Periodic inventory system. Include the proof of cost of sales.

b$)$ Perpetual inventory system.