The following is a series of annual sales (in $millions) over an 11-year period (2007 to 2017): Year: 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Sales: 13.0 17.0 19.0 20.0 20.5 20.5 20.5 20.0 19.0 17.0 13.0 a. Construct a time-series plot. b. Does there appear to be any change in annual sales over time? Explain.
