1. Brealey, R. A., Myers, S. C., & Allen, F. (2020). Principles of Corporate Finance (13th ed.). McGraw-Hill Education.
Chapter 2, Section 2-1, "Calculating Present Value": This chapter explicitly defines the formula for present value as PV = Ct / (1 + r)^t. It states, "The rate r is called the discount rate, hurdle rate, or opportunity cost of capital. It is the return that is foregone by investing in the project rather than investing in financial markets." This directly supports using the 12% opportunity rate as the discount rate 'r'.
2. U.S. Office of Management and Budget (OMB). (2023). Circular A-94, Guidelines and Discount Rates for Benefit-Cost Analysis of Federal Programs.
Section 5, "Basic Precepts of Benefit-Cost Analysis": This official government source states, "The conceptually correct discount rate for a given program is the opportunity cost of the resources that it displaces." It further clarifies that future values must be discounted to their present value. This establishes the principle of using an opportunity cost rate for discounting in a governmental context.
3. Massachusetts Institute of Technology (MIT) OpenCourseWare. (2008). 15.401 Finance Theory I, Lecture Notes, Lecture 2: The Time Value of Money.
Page 3, "Present Value": The notes provide the formula PV = C / (1+r)^t and define 'r' as the "discount rate" or "opportunity cost of capital." This academic source confirms the fundamental formula and the correct application of the opportunity rate for calculating the present value of a future cash flow. Available at: https://ocw.mit.edu/courses/15-401-finance-theory-i-fall-2008/resources/mit15401f08lec02/