Given the following projects and their cash flows:

Year	Project Y	Project Z	Project AA	Project AB
0	-7,000	-9,000	-11,000	-13,000
1	2,000	2,500	3,000	3,500
2	2,500	3,000	3,500	4,000
3	3,000	3,500	4,000	4,500
4	3,500	4,000	4,500	5,000

Required:

1. Compute the payback period for each project.
2. If the acceptable payback period is 3 years, which project will you select?
3. Calculate the discounted payback period with a discount rate of 12%.
4. Determine the NPV for each project using a 12% discount rate. Which project has the highest NPV?
5. Which project should be chosen based on the NPV criterion?