William A. answered 03/19/20
Seasoned College Prof Tutoring Algebra, Pre-Calc, Stats and Finance
The consumer price index reflects the cost of a market basket of goods and services for an urban family of four. So, if the price increased from 150 to 165, the percent increase was (165/150 - 1 )*100% = 10%. That would then be the inflation rate between 2008 and 2009.