An Investment project provides cash inflows of $640 per year for 8 years. a. What is the project payback period If the initial cost is $2,7007 (Enter of the project never pays back. Do not round Intermediate calculations and round your answer to 2 decimal places, e.g., 32.16.) b. What is the project payback period If the initial cost is $3,9007 (Enter of the project never pays back. Do not round Intermediate calculations and round your answer to 2 decimal places, e.g.. 32.16.) c. What is the project payback period if the initial cost is $6,8007 (Enter of the project never pays back. Do not round Intermediate calculations and round your answer to 2 decimal places, e... 32.16.) a. Payback period b. Payback period c. Payback period years years years