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The table shows the number of people in North America who use email as a part of their jobs. North American Business Email Users Email Users, m Year (million users) 2005 128.4 2006 135.1 2007 136.9 2008 137.8 2009 140.8 2010 145.2 (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 S x S 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 2019. (Round your answer to three decimal places.) million users Is this estimate found by interpolation or extrapolation? O interpolation O extrapolation