The table shows the number of people in North America who use email as a part of their jobs.North American Business Email Users

Year	Email Users, m (million users)
2005	126.1
2006	127.3
2007	130.8
2008	134.6
2009	135.8
2010	138.7

(a) Write the function for the linear model that gives the number of North American business email users in millions, where x is the number of years since 2005, with data from

0 x 5.

(Round all numerical values to three decimal places.) m(x) =

____million users (b) What is the constant rate of change of the number of North American business email users? (Round your answer to three decimal places.) ____million users per year (c) Use the model to estimate the number of North American business email users in 2017. (Round your answer to three decimal places.) ____million users Is this estimate found by interpolation or extrapolation? interpolation

extrapolation