Determine each project's payback period:
a. A project with an initial outlay of $5,000 results in a single free cash flow of $10,000 after 6 months
b. A project with an initial outlay of $5,000 results in a single free cash flow of $10,000 after 12 months
c. A project with an initial outlay of $10,000 results in a single free cash flow of $5,000 after 5 years
d. A project with an initial outlay of $5,000 results in a single free cash flow of $10, 123 after 2 years