An amusement company maintains records for each video game it installs in an arcade. Suppose that C(t) and R(t) represent the total accumulated costs and revenues (in thousands of dollars), respectively, t years after a particular game has been installed and the derivatives C'(t) and R'(t) are the following functions. C'(t)=3 and R'(t)=8e-0.31 Find the area between the graphs of C' and R' over the interval on the t-axis from 0 to the useful life of the game and interpret the results. What is the useful life of the game? years (Round to the nearest tenth as needed.)