A regression model is appropriate for predicting mortgage amounts from interest rates based on data from the past 26 years, which found a strong negative correlation of -0.84 between the two variables. The regression equation to predict mortgage amounts from interest rates is: Mortgage Amount = 151.9 million - 23.86 million * Interest Rate. Using this equation, if interest rates climbed to 20%, mortgage amounts would be predicted to be around $107 million. However, this prediction should be viewed cautiously since 20% is beyond the range of interest rates in the original data.