Calculate average annual inflation The price index in the year 1993 is 60.
The base at 2012 is 100.
The annual nominal interest rate between 1993 and 2012 is 66% on average.
What is the average annual inflation between 1993 and 2012?
I know that
Inflation = $\frac{X_{t+s}-X_t}{X_t}$x$ 100$
where $X_{t+s}$ is the current year and $X_t$ is the year being compared.
However, when I use this formula with $X_{t+s}=100$ (since it is the base of the index) and $X_t=60$, I just get the annual nominal interest rate of 66.6666%.
What did I do wrong here?
The calculation goes like:
Price index @ 1993 =  60  ==&gt; X_{t+s}=0.6
Price index @ 2012 = 100  ==&gt; X_{t}=1
Number of years from 1993 to 2012 = 2012 -1993 = 19 ==&gt; s=19
$100*((\frac{X_{t+s}}{X_t})^({\frac{1}{s}})-1) = 100*(\frac{1}{0.6} ^{(1/9)}-1)=100*(\sqrt[9]{(5/3)}-1)=5.840007284127$