What kinds of what-if analysis should be conducted to ensure a good decision is made?

What will be an ideal response?

Since the APR on the loan could fluctuate depending on when the loan is signed, the model should be tested with various rates. Also, the model should be tested against different estimated growth rates. Lastly, the model should be tested with various amounts available for investing. If the owners hold off on the renovations until they have some more money saved to invest, then the likelihood of being able to pay off the loan within seven years may be greater.