consumer surplus

Consumer Surplus. Producer Surplus. Total Surplus. How are these concepts used to explain welfare economics? How are these concepts used to explain the benefits of trade? How are these concepts used to explain why restricting trade reduces societal wellbeing?

(Should trade be restricted in some circumstances, like the sale of organs ect, or should these ideas apply to these circumstances too?)

(Use the concepts from Chapter 7 and 8, and elaborate on some practical impact you find from the chapter. Dont feel limited by the prompt.)