XYZ Ltd. has two projects under consideration. Project Alpha requires an initial investment of $150,000 and will yield returns of $50,000, $60,000, and $70,000 over the next three years. Project Beta requires $180,000 and will yield $60,000, $70,000, and $80,000 over the next three years. The firm's discount rate is 12%.

a) Calculate the NPV of both projects.

b) Determine the IRR of both projects.

c) Identify which project should be pursued.

d) Discuss the significance of the difference in NPVs and IRRs.