College Algebra question

Question

There were 4.32 million licensed drivers in Arizona in 2009 and 3.78 million in 2004. Find a formula for the number, , of licensed drivers in the US as a function of , the number of years since 2004, assuming growth is

Linear:

Answer 1

slope is m=0.54 million over 5 years = 0.108

Since (0, 3.78) is a point on the line, AND it is y-intercept,

the equation is f(t) = 0.108t + 3.78 where t = x-2004, x=2004,2005,2006,....