I am trying to figure out how to value a property (piece of land) based on the original purchase price, and shifted proportional to irregular government valuations.
This is for the purpose of a legal contract, to decide what price a property will be purchased in the future.
Our government values a piece of land at irregular periods. So for example (not the actual figures),
in year 2000 it might have been $100k
in 2006 $140k
in 2008 $130k
in 2014 $150k
Lets say the property was purchased for a figure of $170k in 2012
The "value" is expected to be proportional to purchase price and changed in line with the government valuations.
How would I go about calculating this new "value"?
I was looking at Lagrange (using online calculators) for getting a curve of government valuations. Would you consider this a fair way?
ps. Its been decades since I did any serious maths... ;)