Final answer:
Roberto Company uses a perpetual inventory system, which allows for real-time tracking of inventory.
Step-by-step explanation:
The inventory system used by Roberto Company is a perpetual inventory system.
A perpetual inventory system is a method of tracking inventory in real-time, where each purchase and sale is immediately recorded in the inventory account. This allows a company to have a constant and up-to-date record of the quantity and value of its inventory.
In this case, Roberto Company purchased $3,300 of merchandise for cash on December 1. With a perpetual inventory system, this purchase would be immediately recorded in the inventory account, ensuring that the company has an accurate and current record of its inventory.