Final answer:
The better choice of project, either for an infinite planning horizon or a 10-year horizon, at a MARR of 12% would be the one with the higher present worth. The specifics for projects B1 and B2 are needed to make the determination.
Step-by-step explanation:
The question revolves around the concept of present worth analysis, which is an important engineering economic principle used to compare the value of different projects or investment options considering the time value of money. When the Minimum Attractive Rate of Return (MARR) is fixed at 12%, it implies that any project must offer a return at least this high to be considered viable.
(A) For an infinite planning horizon, one normally uses present worth or net present value (NPV) as the comparison criterion. Since the present worths for projects B1 and B2 are not specified in your question, the selection would normally go to the project with the higher present worth when compared at the MARR of 12%. The higher present worth indicates that over an infinite horizon, that project would yield a better return on investment than the alternative when discounted at the MARR.
(B) With a limited planning horizon of 10 years, the process does not fundamentally change, but it accounts for the return within the specific period. The project with the higher present worth over the 10-year period at the 12% MARR would be preferable as it indicates a higher value of cash flows when both future benefits and costs are brought to their present values using the specified interest rate.