The financial managers of ABDN ple are considering four projects with the following initial investments and cash-flows: Given their own riskiness, investors require 15% return on project 1 and 2 , and 20% return on project 3 and 4 . a) Compute the pay-back period for all the above projects. Which project will ABDN ple choose if the company uses a two-year payback period rule? (30 marks) b) Compute NPV for all the above projects. Assuming that all the projects are NOT mutually exclusive, which project should ABDN ple choose? Carefully explain the similarity or difference between your answer here compared to part a). (30 marks) c) Now let's assume that project 1 and 2 are mutually exclusive, meaning that ABDN ple will not need both projects 1 and 2 . Taking into account the difference in initial investment and pattern of cash flow, should ABDN ple choose project 1 or 2 ? Carefully demonstrate your answer with necessiry calculation. (40 marks)