What are the internal rates of return for the following projects?
a. An initial outlay of $10,000 resulting in a single cash inflow of $17,182 in 8 years
b. An initial outlay of $10,000 resulting in a single cash inflow of $48,077 in 10 years
c. An initial outlay of $10,000 resulting in a single cash inflow of $115,231 in 20 years
d. An initial outlay of $10,000 resulting in a single cash inflow of $13,680 in 3 years