Marginal utility is A. the total utility received from consuming a certain quantity of a good divided by the quantity. B. the utility received from consuming one unit of a good. C. the change in total utility due to a one-unit change in the quantity of a good consumed. D. the utility received by the last consumer of a good.

The correct answer is letter "C": the change in total utility due to a one-unit change in the quantity of a good consumed.

Explanation:

Utility is the satisfaction or joy an individual perceives from consuming a good or service. Marginal utility is the satisfaction that consuming one more unit of the same good or service represents for the same individual. Total utility refers to the aggregate utility of consuming a certain quantity of products.

In such a case, marginal utility can also be understood as the change in total utility that consuming one more unit of a good or service causes.

u = 30

continuing your method

= +

subtract from both sides

= - thus

= -

= ⇒ u = 30