9. The GDP deflator in Russia is 100 in 2015. The deflator rises to 103 in 2016, 109 in 2017, and 120 in 2018.

a. What is the annual rate of inflation over the two-year period from 2015 to 2017? In other words, what constant yearly rate of inflation would lead to the price rise observed over those two years?

b. What is the annual rate of inflation between 2017 and 2018? What is the annual rate of inflation over the three-year period from 2015 to 2018?

c. In general, if P0 is the price level at the beginning of an n-year period, and Pn is the price level at the end of that period, the annual rate of inflation P over that period satisfies the equation 11 + p2n = Pn>P0.