If an endowment fund currently has $100 mil and wants to make the value of portfolio no less than $180 mil in ten years time. They have objective to...

If an endowment fund currently has $100 mil and wants to make the value of portfolio no less than $180 mil in ten years time. They have objective to meet CPI plus 4% over rolling 3-year periods. How should I calculate the required rate of return, for the return objective in the IPS?

Thank you!