Final answer:
To calculate the cost of goods sold using a periodic inventory system, determine the total cost of buying the basket in each time period by adding up the cost of each individual item purchased.
Step-by-step explanation:
To calculate the cost of goods sold for Robin, Inc. using a periodic inventory system, you need to determine the total cost of buying the basket in each time period. This can be done by adding up the cost of each individual item purchased during each time period. For example, if in Time 1 Robin, Inc. purchased 10 items at $2 each, and in Time 2 they purchased 15 items at $3 each, the total cost of buying the basket in Time 1 would be 10 x $2 = $20, and the total cost in Time 2 would be 15 x $3 = $45.