How would you work out a percentage of depreciation for example if something cost 5500 pounds new then 9 years later it costs 2047.08 pounds what formula could you use?

Answer 1

Hold on to your hat!

Suppose the rate of depreciation is p percent per year.

Current value = Start Value*(1 - percentage/100)years

That gives

2047.08 = 5500*(1 - p/100)9

So 0.3722 = (1 - p/100)9

or log(0.3722) = 9*log(1-p/100)

-0.4292 = 9*log(1-p/100)

-0.0477 = log(1-p/100)

10-0.0477 = 1-p/100

0.8960 = 1-p/100

p/100 = 1 - 0.8960 = 0.1040

and, finally, p = 0.1040*100 = 10.4%