ABC Corporation is evaluating two mutually exclusive projects, Project Alpha and Project Beta, both requiring an initial investment of USD 50,000. The expected after-tax cash inflows for each project are as follows:

Year	Cash Flows (Project Alpha)	Cash Flows (Project Beta)
Initial Investment	(50,000)	(50,000)
1	15,000	10,000
2	15,000	20,000
3	10,000	15,000
4	10,000	20,000

a. Calculate the payback period for Project Alpha and Project Beta.

b. Which project should the company invest in and why? Use the Net Present Value (NPV) method assuming a discount rate of 6%.