The Number of Pairs of Sunglasses Sold Each Quarter in a Beachside

Essay

The number of pairs of sunglasses sold each quarter in a beachside drugstore were recorded for the years 2007-2010. These data are shown in the following table. $$\begin{array}{l}\quad\quad\quad\quad\quad\quad\quad\quad\quad\text { Year }\\\begin{array} { | c | c c c c | } \hline \text { Quarter } & 2007 & 2008 & 2009 & 2010 \\\hline 1 & 82 & 84 & 85 & 90 \\2 & 72 & 71 & 70 & 74 \\3 & 65 & 66 & 67 & 71 \\4 & 53 & 54 & 56 & 58 \\\hline\end{array}\end{array}$$ a. Develop a regression model, using indicator variables to represent quarters.
b. Forecast the quarterly earnings for the years 2011 and 2012.