Question 4 (25 marks) The data of average salary of high school teachers in a city from year 2000 to 2015 are shown below. The salary is in IDR million / month. 2000 3.33 2008 4.30 2001 3.67 2009 4.62 2002 3.69 2010 4.66 2003 3.77 2011 4.72 2004 3.84 l 2012 4.82 2005 3.88 2013 4.89 2006 4.02 2014 4.91 2007 4.15 2015 4.94 a. Create a scatter plot for your time series data, and observe the pattern. (5 marks) b. Fit a 3rd-order autoregressive model to the teacher salary. (10 marks) c. Forecast the teacher salary for year 2016. (5 marks) d. Forecast the teacher salary for year 2017