Depreciation

[scallywag1000]

Hi

I am trying to work out the time in years for an area of untransformed land to decrease in area to a specified area (target) through transformation. The starting area is 8420275 and the closing area is 5450191
The area is decreasing by 1.3934% per year. This was calculated using the RATE function in Excel. Can you help me with what function I should use. I am not sure if I could use one of the Depreciation values.

Thanks

Ray

[6StringJazzer]

How did you use RATE if you don't have the number of years to start with? The first argument to RATE is the number of periods. Can you show your formula?

[ron2k_1]

Straight line method:
(8420275-5450191)/(8420275*1.3934%) = 25.3 years

Reducing balance, I think you can use the present value formula:
PV = FV/(1+Rate)^Y ; where:
PV = 5450191
FV=8420275
Rate=0.013934
Y=Years

I cannot remember my algebra class on how to solve for indeces. But solve for Y and I think that should give years.

[scallywag1000]

Thanks for reply

I used the RATE function to calculate the Rate of Change for two landcover totals 12 years apart, i.e. 8420275 (1994) and 7115375 (2006). The formula I used was =Rate(12,,-8420275,7115375,0)

What I am trying to do is see how long in years it would take to reach an area of 5450191 ha at the same rate of change i.e. 1.3934%

[shg]

=log(8420275/5450191, 1-1.3934%) ~ 31 years

[scallywag1000]

Thanks, I am going to use this in my spreadsheet. Serious need to refresh the memory banks with regards algebra etc. I need to read up on reducing balance vs straight line.

Cheers