Final answer:
When a firm's production costs decrease, assuming all other factors are constant (ceteris paribus), it typically increases its quantity produced as the supply curve shifts to the right.
Step-by-step explanation:
If ceteris paribus, which means 'all other things being equal,' a firm's production costs decrease, then the firm is likely to increase its quantity produced. This happens because lower production costs lead to higher profit margins at any given selling price for the firm's products. A decrease in production costs effectively shifts the supply curve to the right, indicating an increase in supply. Therefore, under the assumption of ceteris paribus, a decrease in production costs usually results in a higher quantity of goods being produced by the firm.