calculating irr, payback and a missisng cash flow.

the merriweather printing company is trying to decide on the merits of constructing a new publushing facility. the project is expected to provide a series of positive cash flows for each of the next four years. the estimated cash flows associated with this project are as follows

year project cash flow

0 ?

1 $780,000

2 $420,000

3 $310,000

4 $480,000

if you know that the project has a regular payback of 2.6 years what is the project's IRR?

the IRR of the project is %