Question: The CEO noticed that he has five years of quarterly sales data in hand, and they form a time series. He decided to also ask you to perform time-series analysis on it, and use it to forecast what future sales are expected to be at the end of 4Q 2007.

Plot the quarterly sales as a function of time in your Excel data spreadsheet, and determine what type of trend model would be suitable for this data. Write down the equation for the trend model, and define and explain each of the variables as it applies to this problem. (10 pts)