What is the answer to "Part C" ? It isn't 8.78. I can't seem to get the correct answers.

An investment project provides cash inflows of $1,275 per year for eight years. a. What is the project payback period if the initial cost is $4,100? (Do not round intermediate calculations and round your answers to 2 decimal places, e.g., 32.16.) b. What is the project payback period if the initial cost is $5,150? (Do not round intermediate calculations and round your answers to 2 decimal places, e.g., 32.16.) c. What is the project payback period if the initial cost is $11,200? (Enter 0 if the project never pays back. Do not round intermediate calculations and round your answers to 2 decimal places, e.g., 32.16.) a. Payback period years b. Payback period years C. Payback period years